ci: narrow Python support to 3.12-3.14 (#356)

ComfyUI recommends 3.13, names 3.12 as the fallback and 3.14 as working
(its README); PromptManager supports exactly those. requires-python is
>=3.12, the test matrix and the required checks drop 3.11, and bandit
runs on 3.12.

.github/workflows/code-quality.yml

@@ -26,10 +26,10 @@ jobs:
     steps:
       - uses: actions/checkout@v7
 
-      - name: Set up Python 3.11
+      - name: Set up Python 3.12
         uses: actions/setup-python@v7
         with:
-          python-version: "3.11"
+          python-version: "3.12"
 
       - name: Install bandit
         run: pip install bandit[toml]