updated project style guidelines

lib/api/webuntis/queries/getRooms/getRooms.dart

@@ -9,7 +9,7 @@ class GetRooms extends WebuntisApi {
 
   @override
   Future<GetRoomsResponse> run() async {
-    String rawAnswer = await query(this);
+    var rawAnswer = await query(this);
     try {
       return finalize(GetRoomsResponse.fromJson(jsonDecode(rawAnswer)));
     } catch(e, trace) {
@@ -20,4 +20,4 @@ class GetRooms extends WebuntisApi {
     throw Exception('Failed to parse getRoom server response: $rawAnswer');
   }
 
-}
+}