DOC: adding .gitlab-ci.yml

.gitlab-ci.yml

+image: 'maven:3.8.5-openjdk-17-slim'
+
+cache:
+  paths:
+    - .m2/repository
+
+variables:
+  MAVEN_OPTS: "-Dmaven.repo.local=$CI_PROJECT_DIR/.m2/repository"
+  MAVEN_CLI_OPTS: "--batch-mode --errors --fail-at-end --show-version"
+
+stages:
+  - build
+  - test
+
+build:
+  tags:
+    - shared-fi
+  stage: build
+  script:
+    - echo "We are building your project, $GITLAB_USER_LOGIN"
+    - ./mvnw clean install -Dmaven.test.skip=true $MAVEN_CLI_OPTS
+  artifacts:
+    expire_in: 10 min
+    paths:
+      - "*/target/*.jar"
+
+test:
+  tags:
+    - shared-fi
+  stage: test
+  script:
+    - echo "We are testing your project build, $GITLAB_USER_LOGIN"
+    - ./mvnw test $MAVEN_CLI_OPTS
+  artifacts:
+    expire_in: 10 min
+    paths:
+      - "*/target/*.jar"
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