Remove templates repo reference

Removed deprecated dependent repository configuration for themes.

Author: gewarren

.openpublishing.publish.config.json

@@ -33,13 +33,7 @@
   "need_pr_comments": false,
   "contribution_branch_mappings": {},
   "dependent_repositories": [
-    {
-      "path_to_root": "_themes",
-      "url": "https://github.com/Microsoft/templates.docs.msft",
-      "branch": "main",
-      "branch_mapping": {}
-    },
-    {
+   {
       "path_to_root": "_themes.pdf",
       "url": "https://github.com/Microsoft/templates.docs.msft.pdf",
       "branch": "main",