Bump imageio from 2.32.0 to 2.33.1 in /requirements (#352)

Bumps [imageio](https://github.com/imageio/imageio) from 2.32.0 to 2.33.1.
- [Release notes](https://github.com/imageio/imageio/releases)
- [Changelog](https://github.com/imageio/imageio/blob/master/CHANGELOG.md)
- [Commits](imageio/imageio@v2.32.0...v2.33.1)

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

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

requirements/requirements_doc.txt

@@ -1,6 +1,6 @@
 Sphinx<8
 ansys-sphinx-theme==0.12.5
-imageio==2.32.0
+imageio==2.33.1
 nest-asyncio==1.5.8
 notfound==1.0.2
 pypandoc==1.12