Bump Python requirement to >=3.11, align CI matrix

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

Author: Andrey Golovanov

.github/workflows/python-test.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.11", "3.12", "3.13"]
 
     steps:
       - uses: actions/checkout@v4          # latest stable

pyproject.toml

@@ -10,7 +10,7 @@ readme = "README.md"
 authors = [{ name = "Andrey Golovanov" }]
 license = "MIT"
 license-files = ["LICENSE"]
-requires-python = ">=3.9"
+requires-python = ">=3.11"
 
 classifiers = [
     "Programming Language :: Python :: 3",