Pull the latest wordpress-cli image.

* The latest image doesn't have a user associated with the www-data UID in the WP Image.
* So explicitly use the UID and GID of the user that created the resource files.

Author: Jack-Dane

tests/end_to_end_tests/wordpress-compose.yaml

@@ -32,7 +32,9 @@ services:
       MYSQL_RANDOM_ROOT_PASSWORD: '1'
 
   test_wpcli:
-    user: xfs
+    # 33:33 is the UID of the www-data user that created the WP files.
+    # There isn't a user associated with this UID in the newest WordPress cli container.
+    user: "33:33"
     image: wordpress:cli
     depends_on:
       - test_wordpress