ci: improves ci

.gitlab-ci.yml

 ---
 # Using the official Python Docker image as default
-image: python
+default:
+  image: python
+  before_script:
+    - pip install miss_hit
 
 # Columns of the pipeline
 stages:
   - static analysis
 
 # Static code analysis job via MISS_HIT
-static analysis:
+style_check:
   stage: static analysis
-  before_script:
-    - pip install miss_hit
   script:
-    - mh_style . --fix
     - mh_metric . --ci
+
+metric_check:
+  stage: static analysis
+  script:
+    - mh_metric . --ci
+
+lint_check:
+  stage: static analysis
+  script:
     - mh_lint .
-  allow_failure: false