require Python 3.11

Python 3.9 reached end of life in October 2025, and 3.11 is where the
current ecosystem sits: it unlocks pyarrow 25 (we were held at 21, the
last release supporting 3.9), more-itertools 11, and pandas 3 for the
test suite, along with the large CPython 3.11 interpreter speedups on
exactly the kind of CPU-bound work wikiq does. Nothing in the code
needed changes.

Raising the floor exposed that PyPI's yamlconf 0.2.6 (a transitive
dependency via deltas) pins pyyaml == 5.4.1, which has no wheels for
3.11+ and no longer builds from source under current setuptools. Add a
PEP 508 reference to the fork that loosens the pin; it can be dropped
when https://github.com/halfak/yamlconf/pull/10 is merged and released.

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

.python-version

@@ -1 +1 @@
-3.9
+3.11

pyproject.toml

@@ -3,7 +3,7 @@ name = "mediawiki-dump-tools"
 version = "0.1.1"
 description = "Add your description here"
 readme = "README.md"
-requires-python = ">=3.9"
+requires-python = ">=3.11"
 dependencies = [
     "deltas>=0.7.0",
     "mediawiki-utilities>=0.4.18",
@@ -16,6 +16,10 @@ dependencies = [
     "pyarrow>=20.0.0",
     "pywikidiff2 @ git+https://gitea.communitydata.science/groceryheist/pywikidiff2.git",
     "sortedcontainers>=2.4.0",
+    # PyPI yamlconf 0.2.6 pins pyyaml == 5.4.1, which cannot build on
+    # Python >= 3.11; this fork loosens the pin. Drop once upstream
+    # releases with a fixed requirement.
+    "yamlconf @ git+https://github.com/groceryheist/yamlconf",
 ]
 
 [project.scripts]