Bump sphinx from 8.2.3 to 9.0.4

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 8.2.3 to 9.0.4.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v8.2.3...v9.0.4)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-version: 9.0.4
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

doc/requirements.txt

@@ -1,7 +1,7 @@
 click==8.3.1
 entrypoints==0.4
 Pillow==12.0.0
-Sphinx==8.2.3
+Sphinx==9.0.4
 furo==2025.12.19
 ipython==9.8.0
 netCDF4==1.7.3