sagemathgh-38549: Prepare sage for sphinx 8

    
This PR prepares sage for sphinx 8. An update for sage_autodoc.py is
needed and is provided in this PR.
The minimum known version of sphinx supporting the updated
sage_autodoc.py is 7.4.7. So, sphinx is updated from 7.3.7 (which is
known not to work) to 7.4.7.


### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.
    
URL: sagemath#38549
Reported by: François Bissey
Reviewer(s):

build/pkgs/sphinx/checksums.ini

@@ -1,4 +1,4 @@
 tarball=sphinx-VERSION-py3-none-any.whl
-sha1=8128e17c3c013a91df4c08fc905db5a7e5f63dbf
-sha256=413f75440be4cacf328f580b4274ada4565fb2187d696a84970c23f77b64d8c3
+sha1=f9af5608fbb188f12e38d3c09cdefeef40255365
+sha256=c2419e2135d11f1951cd994d6eb18a1835bd8fdd8429f9ca375dc1f3281bd239
 upstream_url=https://pypi.io/packages/py3/s/sphinx/sphinx-VERSION-py3-none-any.whl

build/pkgs/sphinx/package-version.txt

@@ -1 +1 @@
-7.3.7
+7.4.7

build/pkgs/sphinx/version_requirements.txt

@@ -1 +1 @@
-sphinx >=5.2, <8
+sphinx >=7.4.7, <9