Add gitlab ci file

.gitlab-ci.yml

+build:
+  script:
+    - cp $APP_RELEASE_GRADLE app/release.gradle
+    - cp $LOCAL_PROPERTIES local.properties
+    - ./generate-version.sh
+    - ./gradlew :app:bundle
+  artifacts:
+    paths:
+      - app/build
+      - changelog/build
+deploy:
+  script:
+    - cp $KEYS_JSON app/keys.json
+    - ./gradlew publishReleaseBundle --track internal
+  after_script:
+    - rm -rf app/keys.json
+  rules:
+    - if: '$CI_COMMIT_BRANCH == "develop"'
+      when: always
\ No newline at end of file