Ignore updates of buildpack (e.g. second cf push)

Co-authored-by: Ulrich Kramer <u.kramer@sap.com>

Author: domdom82

app/models/runtime/kpack_lifecycle_data_model.rb

@@ -38,8 +38,12 @@ def buildpacks
       []
     end
 
+    def buildpacks=(new_buildpacks) end
+
     def stack
       nil
     end
+
+    def stack=(new_value) end
   end
 end