Use more generic gitlab-ci.yml

.gitlab-ci.yml

@@ -5,22 +5,25 @@ stages:
 
 variables:
   PYTHON_VERSION: "3.11"
-  PYTHON_IMAGE: "${CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX}/python:${PYTHON_VERSION}-alpine3.18"
+  PYTHON_IMAGE: "python:${PYTHON_VERSION}"
+
+
+.common:
+  image: ${PYTHON_IMAGE}
+  before_script:
+    - pip install -r test_requirements.txt
+    - pip freeze > test_requirements.freeze
+    - python --version
 
 python:
+  extends: .common
   stage: lint
-  image: "${PYTHON_IMAGE}"
   script:
-    - pip install -r test_requirements.txt
     - flake8 .
 
 unittest:
+  extends: .common
   stage: test
-  image: "${PYTHON_IMAGE}"
-  before_script:
-    - pip install -r test_requirements.txt
-    - pip freeze > test_requirements.freeze
-    - python --version
   script:
     - pytest tests
     - coverage run --source errata_server `which pytest` tests