ci: drop Python 3.9 and 3.10 from the test matrix

Signed-off-by: Ben Copeland <ben.copeland@linaro.org>

Author: bhcopeland

.claude/scheduled_tasks.lock

@@ -0,0 +1 @@
+{"sessionId":"f11e614e-83d7-4bb5-8217-cfc414e4df20","pid":545063,"procStart":"146275048","acquiredAt":1779709478744}

.github/workflows/basic-ci.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.11", "3.12"]
 
     steps:
     - uses: actions/checkout@v4