chore(deps): update dependency setuptools to v50.3.2 (#813)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [setuptools](https://togithub.com/pypa/setuptools) | patch | `==50.3.1` -> `==50.3.2` |

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### Release Notes

<details>
<summary>pypa/setuptools</summary>

### [`v50.3.2`](https://togithub.com/pypa/setuptools/blob/master/CHANGES.rst#v5032)

[Compare Source](https://togithub.com/pypa/setuptools/compare/v50.3.1...v50.3.2)

Documentation changes
^^^^^^^^^^^^^^^^^^^^^

-   [#&#8203;2394](https://togithub.com/pypa/setuptools/issues/2394): Extended towncrier news template to include change note categories.
    This allows to see what types of changes a given version introduces
    \-- by :user:`webknjaz`
-   [#&#8203;2427](https://togithub.com/pypa/setuptools/issues/2427): Started enforcing strict syntax and reference validation
    in the Sphinx docs -- by :user:`webknjaz`
-   [#&#8203;2428](https://togithub.com/pypa/setuptools/issues/2428): Removed redundant Sphinx `Makefile` support -- by :user:`webknjaz`

Misc
^^^^

-   [#&#8203;2401](https://togithub.com/pypa/setuptools/issues/2401): Enabled test results reporting in AppVeyor CI
    \-- by :user:`webknjaz`
-   [#&#8203;2420](https://togithub.com/pypa/setuptools/issues/2420): Replace Python 3.9.0 beta with 3.9.0 final on GitHub Actions.
-   [#&#8203;2421](https://togithub.com/pypa/setuptools/issues/2421): Python 3.9 Trove classifier got added to the dist metadata
    \-- by :user:`webknjaz`

</details>

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requirements.txt

@@ -1,5 +1,5 @@
 # Pin to less than 49.6.0 as a workaround for https://github.com/pypa/setuptools/issues/2353
-setuptools==50.3.1
+setuptools==50.3.2
 
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