Update .gitlab-ci.yml

.gitlab-ci.yml

-staging:
-  stage: deploy
-  script:
-    - apk install alpine
-    - apk install lowdown
-    - script.sh
-  environment: staging
+image: alpine:3.15
+stages:
+  - main
+script:
+  - apk install lowdown
+  - ./script.sh
\ No newline at end of file