chore(deps): update dependency python to 3.14

Author: renovate[bot]

.github/workflows/charms_lint_and_unit.yaml

@@ -41,7 +41,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v6
         with:
-          python-version: "3.12"
+          python-version: "3.14"
 
       - name: Set up uv
         uses: astral-sh/setup-uv@v7