Update sphinx requirement from <9.0.0,>=7.0.0 to >=7.0.0,<10.0.0

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/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v7.0.0...v9.0.0)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-version: 9.0.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

pyproject.toml

@@ -34,7 +34,7 @@ Documentation = "https://flogin.readthedocs.io/en/latest/"
 
 [project.optional-dependencies]
 docs = [
-    "sphinx>=7.0.0,<9.0.0",
+    "sphinx>=7.0.0,<10.0.0",
     "furo==2025.7.19", # theme // https://pradyunsg.me/furo/customisation/announcement/
     "sphinx-toolbox>=3.5,<5.0",  # https://sphinx-toolbox.readthedocs.io/en/latest/extensions/index.html
     "sphinxcontrib-trio==1.1.2",