build(deps): bump ansys-sphinx-theme in /requirements

Bumps [ansys-sphinx-theme](https://github.com/ansys/ansys-sphinx-theme) from 1.0.7 to 1.0.8.
- [Release notes](https://github.com/ansys/ansys-sphinx-theme/releases)
- [Commits](ansys/ansys-sphinx-theme@v1.0.7...v1.0.8)

---
updated-dependencies:
- dependency-name: ansys-sphinx-theme
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements/requirements_doc.txt

@@ -1,5 +1,5 @@
 Sphinx<9
-ansys-sphinx-theme==1.0.7
+ansys-sphinx-theme==1.0.8
 imageio==2.35.1
 nest-asyncio==1.6.0
 notfound==1.0.2