ci(djinit/templates/project/ci): remove legacy Python versions from CI matrix

- New Features
  - Updated CI matrix to test Python 3.12 and 3.13.
- Enhancements
  - Dropped support for Python 3.10 and 3.11.
  - Reduces CI runtime and resource consumption.
- Bug Fixes
  - No bug fixes included.

djinit/templates/project/ci/github_actions.j2

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.12", "3.13"]
 
     services:
       postgres: