fix: docker volume getting bloated

Now executing docker system prune before every run to clean unnecessary data and prevent volume from reaching 100%.

.gitlab-ci.yml

@@ -7,6 +7,8 @@ deploy_test:
   variables:
     DOCKER_HOST: unix:///var/run/docker.sock
   script:
+    - echo "Clearing docker data..."
+    - docker system prune
     - echo "Deploying application to test server..."
     - docker volume create nustar_data || true
     - docker volume create nustar_public_media || true
@@ -35,6 +37,8 @@ deploy_production:
   variables:
     DOCKER_HOST: unix:///var/run/docker.sock
   script:
+    - echo "Clearing docker data..."
+    - docker system prune
     - echo "Deploying application to production server..."
     - docker volume create nustar_data || true
     - docker volume create mongo_data || true