contrib: fix a bug in apiage.py

Probably caused by last minute changes to the pr that added the feature,
it just needed the same initialization as the other section.

Signed-off-by: John Mulligan <jmulligan@redhat.com>

contrib/apiage.py

@@ -489,6 +489,7 @@ def main():
             sys.exit(1)
     elif cli.mode == "promote":
         values = {}
+        api_src = _get_api_src()
         _setif(values, "added_in_version", cli.added_in_version)
         ccount, pcount = api_promote(
             api_tracked,