chore: drop Python 3.10 support, require Python 3.11+

CI, packaging metadata, and docs now reflect Python 3.11 as the minimum
supported version. Also collapses the sys.version_info compat shims in
superset/app.py, superset/middleware/legacy_prefix_redirect.py, and
superset/utils/backports.py, which existed solely to support running on
Python 3.10 (StrEnum and wsgiref.types were both added in 3.11).

Removing the 3.10 floor also drops the now-dead pyhive<0.7.0 marker for
python_version<'3.11' and obsoletes the need to pin syntaqlite below
0.5.0 for 3.10 compatibility.

Closes #42007

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.github/workflows/bump-python-package.yml

@@ -42,7 +42,7 @@ jobs:
       - name: Set up Python ${{ inputs.python-version }}
         uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6.3.0
         with:
-          python-version: "3.10"
+          python-version: "3.11"
 
       - name: Install uv
         run: pip install uv