Update sphinx requirement from ==5.* to ==7.* (#450)

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@v5.0.0b1...v7.2.6)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pyproject.toml

@@ -29,7 +29,7 @@ dependencies = [
     "cwl-utils==0.*",
     "myst-parser==2.*",
     "pydata-sphinx-theme==0.*",
-    "sphinx==6.*",
+    "sphinx==7.*",
     "sphinx-reredirects==0.1.*",
     "sphinxcontrib-runcmd==0.2.*",
     "sphinx-favicon",