Bump sphinx-notfound-page from 0.8 to 0.8.3

Bumps [sphinx-notfound-page](https://github.com/readthedocs/sphinx-notfound-page) from 0.8 to 0.8.3.
- [Release notes](https://github.com/readthedocs/sphinx-notfound-page/releases)
- [Changelog](https://github.com/readthedocs/sphinx-notfound-page/blob/main/CHANGELOG.rst)
- [Commits](readthedocs/sphinx-notfound-page@0.8...0.8.3)

---
updated-dependencies:
- dependency-name: sphinx-notfound-page
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs/requirements.txt

@@ -83,7 +83,7 @@ sphinx-autoapi==1.8.4
     # via sphinx-hoverxref (pyproject.toml)
 sphinx-autobuild==2021.3.14
     # via sphinx-hoverxref (pyproject.toml)
-sphinx-notfound-page==0.8
+sphinx-notfound-page==0.8.3
     # via sphinx-hoverxref (pyproject.toml)
 sphinx-prompt==1.5.0
     # via sphinx-hoverxref (pyproject.toml)