build: Upgrade sphinx and remove packaging upper bound (#8183)

Remove `packaging` upper bound to resolve `virtualenv` vulnerability reports.
Remove `sphinx` upper bound, since the `sphinx` version required legacy `packaging` versions.
Remove legacy from `docs/conf.py` that caused exceptions on new `sphinx` versions.

Author: alexander-alderman-webb

docs/conf.py

@@ -1,21 +1,7 @@
 import os
 import sys
-import typing
 from datetime import datetime
 
-# prevent circular imports
-import sphinx.builders.html
-import sphinx.builders.latex
-import sphinx.builders.texinfo
-import sphinx.builders.text
-import sphinx.domains.c  # noqa: F401
-import sphinx.domains.cpp  # noqa: F401
-import sphinx.ext.autodoc  # noqa: F401
-import sphinx.ext.intersphinx  # noqa: F401
-import urllib3.exceptions  # noqa: F401
-
-typing.TYPE_CHECKING = True
-
 #
 # Configuration file for the Sphinx documentation builder.
 #

pyproject.toml

@@ -16,15 +16,15 @@ dev = [
 
 toxgen = [
     "jinja2",
-    "packaging<26.0",
+    "packaging",
     "pip",
     "requests",
 ]
 
 docs = [
     "gevent",
     "shibuya",
-    "sphinx<8.2",
+    "sphinx",
     "sphinx-autodoc-typehints[type_comments]>=2.3.0",
     "typing-extensions",
 ]