added ci for gems

rails/gitlab-ci-for-gem.yml

+variables:
+  CI: "true"
+  RAILS_ENV: test
+
+set_ruby_version:
+  stage: build
+  script:
+    - echo "RUBY_VERSION=$(cat .ruby-version | sed 's/ruby-//g')" >> build.env
+  artifacts:
+    reports:
+      dotenv: build.env
+    expire_in: 1 week
+
+rubocop:
+  stage: test
+  image: ruby:$RUBY_VERSION
+  tags:
+    - gem
+  script:
+    - wget --quiet "https://git-ce.rwth-aachen.de/noc-public/noc-netze-gitlab-cicd/-/raw/main/rails/rubocop.yml" -O ".rubocop.yml"
+    - gem install rubocop:1.75.5 rubocop-capybara:2.22.1 rubocop-minitest:0.38.0 rubocop-performance:1.25.0 rubocop-rails:2.31.0 --silent
+    - gem install itc-gem_rubocop:0.1.4 --source=https://noc-portal.itc.rwth-aachen.de/geminabox --silent
+    - rubocop
+
+erb_lint:
+  stage: test
+  image: ruby:$RUBY_VERSION
+  tags:
+    - gem
+  script:
+    - wget --quiet "https://git-ce.rwth-aachen.de/noc-public/noc-netze-gitlab-cicd/-/raw/main/rails/rubocop.yml" -O ".rubocop.yml"
+    - wget --quiet "https://git-ce.rwth-aachen.de/noc-public/noc-netze-gitlab-cicd/-/raw/main/rails/erb_lint.yml" -O ".erb_lint.yml"
+    - gem install rubocop:1.75.5 rubocop-capybara:2.22.1 rubocop-minitest:0.38.0 rubocop-performance:1.25.0 rubocop-rails:2.31.0 erb_lint:0.9.0 --silent
+    - gem install itc-gem_rubocop:0.1.4 --source=https://noc-portal.itc.rwth-aachen.de/geminabox --silent
+    - erb_lint --lint-all --allow-no-files true
+
+haml_lint:
+  stage: test
+  image: ruby:$RUBY_VERSION
+  tags:
+    - gem
+  script:
+    - wget --quiet "https://git-ce.rwth-aachen.de/noc-public/noc-netze-gitlab-cicd/-/raw/main/rails/rubocop.yml" -O ".rubocop.yml"
+    - wget --quiet "https://git-ce.rwth-aachen.de/noc-public/noc-netze-gitlab-cicd/-/raw/main/rails/haml-lint.yml" -O ".haml-lint.yml"
+    - gem install rubocop:1.75.5 rubocop-capybara:2.22.1 rubocop-minitest:0.38.0 rubocop-performance:1.25.0 rubocop-rails:2.31.0 haml_lint:0.62.0 --silent
+    - gem install itc-gem_rubocop:0.1.4 --source=https://noc-portal.itc.rwth-aachen.de/geminabox --silent
+    - haml-lint
+
+test:
+  stage: test
+  image: ruby:$RUBY_VERSION
+  tags:
+    - gem
+  script:
+    - gem install bundler --silent
+    - bundle install --jobs $(nproc) --quiet
+    - rake test