(ci) Remove runners tags

Doesn’t make sense anymore
Was set up to load equaly the load onto the two runners
I am fine with the fact that runners takes the jobs by
themselves dependending on their availabilities

.gitlab-ci.yml

@@ -61,7 +61,6 @@ lint:
     - .code_changes
     - .pre-commit
   stage: checks
-  tags: [redshift]
   script:
     - pre-commit run --all-files pylint
 
@@ -91,26 +90,24 @@ type:
 
 tests:3.7:
   extends: .tests
-  tags: [mille]
   variables:
     PYTHON_VERSION: "3.7"
 
 tests:3.8:
   extends: .tests
-  tags: [redshift]
   variables:
     PYTHON_VERSION: "3.8"
 
 tests:3.9:cov:
   extends: .tests
-  tags: [redshift]
+  variables:
+    PYTHON_VERSION: "3.9"
   script:
     - poetry install
     - poetry run pytest --cov duniterpy --cov-report html:cov_html --cov-report term
 
 tests:3.10:
   extends: .tests
-  tags: [redshift]
   variables:
     PYTHON_VERSION: "3.10"