Update sphinx requirement from <7,>=5 to >=5,<8

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@v5.0.0...v7.2.6)

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

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

pyproject.toml

@@ -51,7 +51,7 @@ test = [
     "fronts[examples]",
 ]
 doc = [
-    "sphinx>=5,<7",
+    "sphinx>=5,<8",
     "sphinx_rtd_theme",
 ]
 dev = [