remove tab (#7692)

Author: nicksanders348

modules/swagger-codegen/src/main/resources/dart/auth/authentication.mustache

@@ -1,7 +1,7 @@
 part of {{pubName}}.api;
 
 abstract class Authentication {
-	
+
 	/// Apply authentication settings to header and query params.
 	void applyToParams(List<QueryParam> queryParams, Map<String, String> headerParams);
-}
+}