Add stopping container and deleting volumes

.travis.yml

@@ -41,6 +41,8 @@ matrix:
       - npm run build
       - docker-compose up --build -d
       - travis_retry bash tests/bin/run-e2e-CI.sh
+    after_script:
+      - docker-compose down -v
   - name: "Unit tests code coverage"
     php: 7.3
     env: WP_VERSION=latest WP_MULTISITE=0 RUN_CODE_COVERAGE=1