Drop Python 3.9-3.11, add 3.13 — CI and metadata now target 3.12 + 3.13

Python 3.9 is EOL since Oct 2025. Standardize on 3.12 + 3.13 across all repos
to match PyAutoBuild and catch forward-compatibility issues early.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 2 people

.github/workflows/main.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.9, '3.10', '3.11', '3.12']
+        python-version: ['3.12', '3.13']
     steps:
     - name: Checkout PyAutoConf
       uses: actions/checkout@v2

pyproject.toml

@@ -8,7 +8,7 @@ dynamic = ["version"]
 description = "Classy Probabilistic Programming"
 readme = { file = "README.rst", content-type = "text/x-rst" }
 license = { text = "MIT" }
-requires-python = ">=3.9"
+requires-python = ">=3.12"
 authors = [
     { name = "James Nightingale", email = "James.Nightingale@newcastle.ac.uk" },
     { name = "Richard Hayes", email = "richard@rghsoftware.co.uk" },
@@ -18,10 +18,8 @@ classifiers = [
   "Topic :: Scientific/Engineering :: Physics",
   "Natural Language :: English",
   "Operating System :: OS Independent",
-  "Programming Language :: Python :: 3.9",
-  "Programming Language :: Python :: 3.10",
-  "Programming Language :: Python :: 3.11",
-  "Programming Language :: Python :: 3.12"
+  "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13"
 ]
 keywords = ["cli"]
 dependencies = [