Test the floor and the versions actually worked on

The matrix ran 3.10, 3.11 and 3.12 while the developer's own environment is
3.14 and the clean-clone check runs 3.10 — so CI covered neither end that is
used, stopping two releases behind the interpreter every local suite run
takes. 3.11 and 3.12 are dropped for 3.13 and 3.14: a defect present in a
middle version and in neither end is rarer than one in the version the
developer runs all day and CI never saw.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019WkxmJ5ArLEaC2RDPGkbRU

Author: jerodw

.github/workflows/tests.yml

@@ -18,7 +18,16 @@ jobs:
       # from a real one, and that distinction is the reason to run three.
       fail-fast: false
       matrix:
-        python-version: ['3.10', '3.11', '3.12']
+        # The floor, and the two the developer actually works on. 3.10 is what
+        # the clean-clone check runs, deliberately older than the working
+        # environment so an incompatibility is found before CI rather than by
+        # it; 3.14 is the interpreter every local suite run uses, and until
+        # 2026-09-09 nothing in CI covered it or the release below it. The
+        # versions between the floor and the ceiling are dropped rather than
+        # kept: a defect present in one of them and in neither end is rarer
+        # than a defect in the version the developer runs all day and CI never
+        # saw.
+        python-version: ['3.10', '3.13', '3.14']
     steps:
       - uses: actions/checkout@v4
         with: