ci: Cache pip files

.gitlab-ci.yml

@@ -6,6 +6,9 @@ lint:
     - pip3 install pylint flake8 black mypy pytest
   script:
     - ./scripts/lint.sh
+  cache:
+    paths:
+      - /root/.cache/pip/
 
 test:
   image: python:alpine
@@ -15,3 +18,6 @@ test:
     - apk add git
   script:
     - pytest
+  cache:
+    paths:
+      - /root/.cache/pip/