feat: adds .gitlab-ci.yml for semantic-release

.gitlab-ci.yml

+# The release pipeline will run only on the releases branch on commit
+stages:
+  - release
+
+release:
+  image: node:12-buster-slim
+  stage: release
+  before_script:
+    - apt-get update && apt-get install -y --no-install-recommends git-core ca-certificates
+    - npm install -g semantic-release @semantic-release/gitlab @semantic-release/git @semantic-release/changelog @ambimax/semantic-release-composer@npm:@iwavesmedia/semantic-release-composer
+  script:
+    - semantic-release
+  rules:
+    - if: $CI_COMMIT_BRANCH == "releases"