[ci] #177: Set Py3.9 as default where pre-commit is installed

.gitlab-ci.yml

@@ -6,7 +6,7 @@ stages:
 
 variables:
   DOCKER_IMAGE: "registry.duniter.org/docker/python3/poetry"
-  PYTHON_VERSION: "3.8"
+  PYTHON_VERSION: "3.9"
 
 image: $DOCKER_IMAGE/$PYTHON_VERSION:latest
 
@@ -96,12 +96,12 @@ tests-3.7:
 tests-3.8:
   extends: .tests
   tags: [redshift]
+  variables:
+    PYTHON_VERSION: "3.8"
 
 tests-3.9:
   extends: .tests
   tags: [redshift]
-  variables:
-    PYTHON_VERSION: "3.9"
 
 release:
   stage: release