Attempt to fix CI (use python venv)

.gitlab-ci.yml

@@ -4,7 +4,9 @@ default:
     entrypoint: [""]
   before_script:
     - apk add --no-cache build-base python3 python3-dev py3-pip ttf-freefont
-    - pip install recipemd
+    - python3 -m venv .venv
+    - source .venv/bin/activate
+    - python3 -m pip install recipemd
 
 check_filenames:
   allow_failure: true