Chore(deps): Bump sphinx from 7.2.2 to 8.1.3

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 7.2.2 to 8.1.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/v8.1.3/CHANGES.rst)
- [Commits](https://github.com/sphinx-doc/sphinx/compare/v7.2.2...v8.1.3)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

docs/requirements.in

@@ -1,2 +1,2 @@
-sphinx<8.0.0
+sphinx<9.0.0
 sphinx_rtd_theme

docs/requirements.txt

@@ -4,15 +4,15 @@
 #
 #    pip-compile --resolver=backtracking requirements.in
 #
-alabaster==0.7.13
+alabaster==1.0.0
     # via sphinx
-babel==2.12.1
+babel==2.17.0
     # via sphinx
 certifi==2024.7.4
     # via requests
 charset-normalizer==3.1.0
     # via requests
-docutils==0.18.1
+docutils==0.21.2
     # via
     #   sphinx
     #   sphinx-rtd-theme
@@ -20,42 +20,38 @@ idna==3.7
     # via requests
 imagesize==1.4.1
     # via sphinx
-importlib-metadata==8.5.0
-    # via sphinx
 jinja2==3.1.5
     # via sphinx
 markupsafe==2.1.2
     # via jinja2
 packaging==23.1
     # via sphinx
-pygments==2.15.1
+pygments==2.19.1
     # via sphinx
 requests==2.32.2
     # via sphinx
 snowballstemmer==2.2.0
     # via sphinx
-sphinx==7.2.2
+sphinx==8.1.3
     # via
     #   -r docs/requirements.in
     #   sphinx-rtd-theme
     #   sphinxcontrib-jquery
 sphinx-rtd-theme==3.0.2
     # via -r docs/requirements.in
-sphinxcontrib-applehelp==1.0.4
+sphinxcontrib-applehelp==2.0.0
     # via sphinx
-sphinxcontrib-devhelp==1.0.2
+sphinxcontrib-devhelp==2.0.0
     # via sphinx
-sphinxcontrib-htmlhelp==2.0.1
+sphinxcontrib-htmlhelp==2.1.0
     # via sphinx
 sphinxcontrib-jquery==4.1
     # via sphinx-rtd-theme
 sphinxcontrib-jsmath==1.0.1
     # via sphinx
-sphinxcontrib-qthelp==1.0.3
+sphinxcontrib-qthelp==2.0.0
     # via sphinx
-sphinxcontrib-serializinghtml==1.1.5
+sphinxcontrib-serializinghtml==2.0.0
     # via sphinx
 urllib3==2.2.2
     # via requests
-zipp==3.21.0
-    # via importlib-metadata