requirements: update matplotlib requirement from <3.7.6 to <3.9.3

[dependabot]

Updates the requirements on matplotlib to permit the latest version.

Release notes

Sourced from matplotlib's releases.

REL: 3.9.2

This is the second bugfix release of the 3.9.x series.

This release contains several bug-fixes and adjustments:

• Be more resilient to I/O failures when writing font cache
• Fix nondeterministic behavior with subplot spacing and constrained layout
• Fix sticky edge tolerance relative to data range
• Improve formatting of image values in cases of singular norms

Windows wheels now bundle the MSVC runtime DLL statically to avoid inconsistencies with other wheels and random crashes depending on import order.

Commits

• a254b68 REL: 3.9.2
• 056f307 DOC: Create release notes for 3.9.2
• 8d867ce Merge branch 'v3.9.1-doc' into v3.9.x
• 7be8675 Merge pull request #28687 from QuLogic/static-msvc
• 3ed3d7b Merge pull request #28695 from meeseeksmachine/auto-backport-of-pr-27797-on-v...
• 8a62afa BLD: Include MSVCP140 runtime statically
• 81be26f Merge pull request #28688 from QuLogic/auto-backport-of-pr-28668-on-v3.9.x
• d88a582 Backport PR #27797: DOC: Use video files for saving animations
• e3159ba Merge pull request #28692 from meeseeksmachine/auto-backport-of-pr-28632-on-v...
• 465401e Backport PR #28632: DOC: Tell sphinx-gallery to link mpl_toolkits from our build
• Additional commits viewable in compare view

You can trigger a rebase of this PR by commenting @dependabot rebase.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot squash and merge will squash and merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge and block automerging
• @dependabot reopen will reopen this PR if it is closed
• @dependabot close will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
• @dependabot show <dependency name> ignore conditions will show all of the ignore conditions of the specified dependency
• @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)

Note
Automatic rebases have been disabled on this pull request as it has been open for over 30 days.

[github-actions]

This PR causes the following changes to the html docs (ubuntu-latest-3.11):

diff -r docs-base/ModulatoryProjection.html docs-head/ModulatoryProjection.html
272c272
< <a class="reference internal" href="Port.html"><span class="doc">Port</span></a> are listed in the Port’s <a class="reference internal" href="Mechanism.html#id7" title="psyneulink.core.components.mechanisms.mechanism.Mechanism_Base.mod_afferents"><code class="xref any py py-attr docutils literal notranslate"><span class="pre">mod_afferents</span></code></a> attribute.</p>
---
> <a class="reference internal" href="Port.html"><span class="doc">Port</span></a> are listed in the Port’s <a class="reference internal" href="ParameterPort.html#psyneulink.core.components.ports.parameterport.ParameterPort.mod_afferents" title="psyneulink.core.components.ports.parameterport.ParameterPort.mod_afferents"><code class="xref any py py-attr docutils literal notranslate"><span class="pre">mod_afferents</span></code></a> attribute.</p>
diff -r docs-base/Port.html docs-head/Port.html
616c616
< <code class="xref any docutils literal notranslate"><span class="pre">PathWayProjections</span></code> (listed in its <a class="reference internal" href="Mechanism.html#id6" title="psyneulink.core.components.mechanisms.mechanism.Mechanism_Base.path_afferents"><code class="xref any py py-attr docutils literal notranslate"><span class="pre">path_afferents</span></code></a> attribute) as the variable for its
---
> <code class="xref any docutils literal notranslate"><span class="pre">PathWayProjections</span></code> (listed in its <a class="reference internal" href="#psyneulink.core.components.ports.port.Port_Base.path_afferents" title="psyneulink.core.components.ports.port.Port_Base.path_afferents"><code class="xref any py py-attr docutils literal notranslate"><span class="pre">path_afferents</span></code></a> attribute) as the variable for its
diff -r docs-base/TransferFunctions.html docs-head/TransferFunctions.html
2361c2361
< <p><a class="reference internal" href="#psyneulink.core.components.functions.transferfunctions.Exponential.bounds" title="psyneulink.core.components.functions.transferfunctions.Exponential.bounds"><code class="xref any py py-attr docutils literal notranslate"><span class="pre">bounds</span></code></a> – specifies the lower and upper limits of the result;  if there are none, the attribute is set to
---
> <p><a class="reference internal" href="OptimizationFunctions.html#psyneulink.core.components.functions.optimizationfunctions.GradientOptimization.bounds" title="psyneulink.core.components.functions.optimizationfunctions.GradientOptimization.bounds"><code class="xref any py py-attr docutils literal notranslate"><span class="pre">bounds</span></code></a> – specifies the lower and upper limits of the result;  if there are none, the attribute is set to

...

See CI logs for the full diff.

[github-actions]

This PR causes the following changes to the html docs (ubuntu-latest-3.11):

No differences!

...

See CI logs for the full diff.

[dependabot]

Superseded by #520.