Build(deps): bump the pip-deps group in /requirements with 3 updates

Bumps the pip-deps group in /requirements with 3 updates: [sphinx](https://github.com/sphinx-doc/sphinx), [ansys-sphinx-theme](https://github.com/ansys/ansys-sphinx-theme) and [matplotlib](https://github.com/matplotlib/matplotlib).


Updates `sphinx` from 7.2.5 to 7.2.6
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v7.2.5...v7.2.6)

Updates `ansys-sphinx-theme` from 0.11.1 to 0.11.2
- [Release notes](https://github.com/ansys/ansys-sphinx-theme/releases)
- [Commits](ansys/ansys-sphinx-theme@v0.11.1...v0.11.2)

Updates `matplotlib` from 3.7.2 to 3.8.0
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](matplotlib/matplotlib@v3.7.2...v3.8.0)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: pip-deps
- dependency-name: ansys-sphinx-theme
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: pip-deps
- dependency-name: matplotlib
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: pip-deps
...

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

requirements/requirements_docs.txt

@@ -1,7 +1,7 @@
-Sphinx==7.2.5
+Sphinx==7.2.6
 jupyter_sphinx==0.4.0
 numpydoc==1.5.0
-ansys_sphinx_theme==0.11.1
+ansys_sphinx_theme==0.11.2
 pypandoc==1.11
 pytest-sphinx==0.5.0
 sphinx-autobuild==2021.3.14
@@ -13,5 +13,5 @@ sphinxcontrib-websupport==1.2.6
 sphinxemoji==0.2.0
 pandas==2.1.0
 pandoc>=2.1
-matplotlib==3.7.2
+matplotlib==3.8.0
 breathe>=4.33.1