Bump pyvista from 0.39.0 to 0.39.1 in /requirements (#256)

Bumps [pyvista](https://github.com/pyvista/pyvista) from 0.39.0 to 0.39.1.
- [Release notes](https://github.com/pyvista/pyvista/releases)
- [Commits](pyvista/pyvista@v0.39.0...v0.39.1)

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

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

requirements/requirements_docs.txt

@@ -3,7 +3,7 @@ ansys-sphinx-theme==0.9.8
 imageio==2.28.1
 notfound==1.0.2
 pypandoc==1.11
-pyvista==0.39.0
+pyvista==0.39.1
 sphinx-copybutton==0.5.2
 sphinx-gallery==0.13.0
 sphinx-notfound-page==0.8.3