Pin prettier version & set role path in CI

.gitlab-ci.yml

@@ -12,7 +12,7 @@ lint:
   stage: lint
   image: node:12
   before_script:
-    - npm install prettier --no-save
+    - npm install
   script:
     - npx prettier '**/*.yml' --check
 
@@ -21,6 +21,6 @@ syntax-test:
   image: python:3.7
   before_script:
     - pip install ansible --quiet
-    - ansible-galaxy install -r requirements.yml
+    - ansible-galaxy install --role-file requirements.yml --roles-path ./roles
   script:
     - ansible-playbook playbook.yml --syntax-check