fix: linter errors

.gitlab-ci.yml

+---
+ansible_lint:
+  image: 'registry.code.fbi.h-da.de/hdacloud/images/netci'
+  script:
+    - ansible-lint

meta/main.yml

 galaxy_info:
   author: hdacloud
   description: Ansible role to deploy oauth2-proxy container as a system service
+  license: MIT
+  min_ansible_version: "2.12"
+  platforms:
+    - name: Ubuntu
 
 dependencies: []