Update source-repositories with IPA builder comments

Added comments regarding IPA builder fork merge.

Author: dougszumski

ansible/inventory/group_vars/all/source-repositories

@@ -241,6 +241,8 @@ source_repositories:
     synced_releases:
       - "2023.1"
       - yoga
+  # We can drop the IPA builder fork when this is merged:
+  # https://review.opendev.org/c/openstack/ironic-python-agent-builder/+/998333
   ironic-python-agent-builder:
     synced_releases:
       - "2025.1"