replace module only if file exists

roles/matrix-awx/tasks/rename_variables.yml

@@ -5,4 +5,5 @@
     path: "/var/lib/awx/projects/clients/{{ member_id }}/{{ subscription_id }}/matrix_vars.yml"
     regexp: 'matrix_synapse_use_presence'
     replace: 'matrix_synapse_presence_enabled'
-
+  args: 
+    creates: "/var/lib/awx/projects/clients/{{ member_id }}/{{ subscription_id }}/matrix_vars.yml"