fix(ci): drop Python 3.9 from test matrix

python_requires was bumped to >=3.10 in setup.py as part of the typer
migration. The CI matrix still included 3.9, causing failures.

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

Author: yeldarby

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         os: ["ubuntu-latest", "windows-latest"]
-        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
     runs-on: ${{ matrix.os }}
     env:
       PYTHONUTF8: 1