Update sphinx requirement from <6,>2 to >2,<9

Updates the requirements on [sphinx](https://github.com/sphinx-doc/sphinx) to permit the latest version.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/v8.0.2/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v2.0.1...v8.0.2)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-type: direct:development
...

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

setup.cfg

@@ -47,7 +47,7 @@ djangocms_page_meta = *.html *.png *.gif *js *jpg *jpeg *svg *py *mo *po
 [options.extras_require]
 docs =
 	django<5.0
-	sphinx>2,<6
+	sphinx>2,<9
 	djangocms-page-tags
 
 [sdist]