Fix KeyError with user query result

The return object could be dictionary when failed auth, which could
cause the KeyError exception. Fix it by also catch the KeyError.

Signed-off-by: Wayne Sun <gsun@redhat.com>

did/plugins/gitlab.py

@@ -125,7 +125,7 @@ def get_user(self, username):
                 ) from jde
         try:
             return result[0]
-        except IndexError:
+        except (IndexError, KeyError):
             raise ReportError(
                 "Unable to find user '{0}' on GitLab.".format(username))