⬆️ Update sphinx requirement from <7,>=4 to >=4,<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)
- [Commits](sphinx-doc/sphinx@v4.0.0...v7.1.0)

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

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

pyproject.toml

@@ -28,7 +28,7 @@ classifiers = [
 ]
 keywords = ["sphinx", "extension", "material design", "web components"]
 requires-python = ">=3.7"
-dependencies = ["sphinx>=4,<7"]
+dependencies = ["sphinx>=4,<8"]
 
 [project.urls]
 Homepage = "https://github.com/executablebooks/sphinx-design"