Update plugins.gitlab-ci.yml

plugins.gitlab-ci.yml

@@ -37,6 +37,9 @@ include:
 # You can uncomment the deploy lines to deploy your project to the CAVE/VRDev. This only makes sense, if your plugin works
 # with a generated project.
 
+variables:
+  UNREAL_VERSION: "5.3"
+
 stages:
   - generate
   - build