⬆️ Update sphinx requirement from ~=8.0.2 to ~=8.1.3 (#158)

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@v8.0.2...v8.1.3)

---
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>
Co-authored-by: Jonathan Chico <[email protected]>

pyproject.toml

@@ -51,7 +51,7 @@ tests = [
 ]
 
 docs = [
-    'sphinx~=8.0.2',
+    'sphinx~=8.1.3',
     'sphinx-copybutton~=0.5.2',
     'sphinx-book-theme~=1.1.2',
     'sphinx-click~=6.0.0',