Add .gitlab-ci.yml

.gitlab-ci.yml

+variables:
+  SONAR_USER_HOME: "${CI_PROJECT_DIR}/.sonar"  # Defines the location of the analysis task cache
+  GIT_DEPTH: "0"  # Tells git to fetch all the branches of the project, required by the analysis task
+sonarcloud-check:
+  image:
+    name: sonarsource/sonar-scanner-cli:latest
+    entrypoint: [""]
+  cache:
+    key: "${CI_JOB_NAME}"
+    paths:
+      - .sonar/cache
+  script:
+    - sonar-scanner
+  only:
+    - merge_requests
+    - master
+    - develop
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