ci: add basic integration test for pmb

Yes, I know this is crude/basic, but others are welcome to improve it later. I think we need some integration testing asap, and this is better than nothing :D

.gitlab-ci.yml

@@ -21,6 +21,7 @@ stages:
 integration:
   stage: test
   before_script:
+    - *global_before_scripts
     - apk upgrade -U
     - apk add python3 git openssl
   script: