Update sphinx requirement from <8,>=3.5 to >=3.5,<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@v3.5.0...v8.0.2)

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

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

setup.py

@@ -72,7 +72,7 @@ def read(path):
               'pueblo>=0.0.7',
               'pytz',
               ],
-        doc=['sphinx>=3.5,<8',
+        doc=['sphinx>=3.5,<9',
              'crate-docs-theme>=0.26.5'],
     ),
     python_requires='>=3.6',