Bump pyvista from 0.39.1 to 0.40.0 in /requirements

Bumps [pyvista](https://github.com/pyvista/pyvista) from 0.39.1 to 0.40.0.
- [Release notes](https://github.com/pyvista/pyvista/releases)
- [Commits](pyvista/pyvista@v0.39.1...v0.40.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements/requirements_docs.txt

@@ -3,7 +3,7 @@ ansys-sphinx-theme==0.9.9
 imageio==2.31.1
 notfound==1.0.2
 pypandoc==1.11
-pyvista==0.39.1
+pyvista==0.40.0
 sphinx-copybutton==0.5.2
 sphinx-gallery==0.13.0
 sphinx-notfound-page==0.8.3