copy-wheels: ensure split actually splits

From the ansible manual

"The difference between single quotes and double quotes is that in
double quotes you can use escapes:"

This turns out to be important when you're splitting based on \n ...

Change-Id: Ia033426bf05a63034fb11882e92d29e3ede8fc53

roles/copy-wheels/tasks/main.yaml

@@ -21,6 +21,6 @@
   args:
     chdir: '{{ item }}'
     executable: 'python3'
-  loop: '{{ directories.stdout.split("\n") }}'
+  loop: "{{ directories.stdout.split('\n') }}"
   # NOTE(ianw) remove after testing
   ignore_errors: true