ci: add python 3.9 ~ 3.12 for codecov

Author: jason810496

.github/workflows/codecov.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.12"]
+        python-version: ["3.9","3.10","3.11","3.12"]
 
     name: Test pgmq-sqlalchemy
     steps: