ci(gitlab): move `npm install` to job script

- global script somehow doesn't work anymore

.gitlab-ci.yml

@@ -4,12 +4,10 @@ cache: # add cache to 'node_modules' for speeding up builds
   paths:
     - node_modules/ # Node modules and dependencies
 
-before_script:
-  - npm install --only=prod
-
 test:
   before_script:
     - 'which ssh-agent || (apk update && apk add openssh-client git)'
+    - npm install --only=prod
 
   script:
     - npm install --only=prod snyk && npm run snyk # Refer to "scripts" in package.json
@@ -45,6 +43,9 @@ test:
       when: always
 
 renovate: # Check dependency update
+  before_script:
+    - npm install --only=prod
+
   script:
     - npm install --only=prod renovate
     - npm run renovate