Update .gitlab-ci.yml (old deployment script)

.gitlab-ci.yml

 include:
   - project: microservices.app.rwth-aachen.de/core/deployment-scripts
-    ref: master
+    ref: issue/test-deployment-scripts
     file: /ci/netcoremicroservice.yml
 
 variables:
   CI_PARENT_PROJECT_URL: $CI_PROJECT_URL
   CI_PARENT_PROJECT_NAME: $CI_PROJECT_TITLE
-  CI_PARENT_INCLUDE_REF: master
+  CI_PARENT_INCLUDE_REF: issue/test-deployment-scripts