Bump vtk from 9.2.2 to 9.2.5 in /requirements (#192)

Bumps [vtk](https://vtk.org) from 9.2.2 to 9.2.5.

---
updated-dependencies:
- dependency-name: vtk
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements/requirements_docs.txt

@@ -6,4 +6,4 @@ pyvista==0.37.0
 sphinx-copybutton==0.5.1
 sphinx-gallery==0.11.1
 sphinx-notfound-page==0.8.3
-vtk==9.2.2
+vtk==9.2.5