Added api for custom timetable events

lib/api/mhsl/customTimetableEvent/update/updateCustomTimetableEvent.dart

@@ -0,0 +1,22 @@
+import 'dart:convert';
+
+import 'package:http/http.dart';
+import 'package:http/http.dart' as http;
+
+import '../../mhslApi.dart';
+import 'updateCustomTimetableEventParams.dart';
+
+class UpdateCustomTimetableEvent extends MhslApi<void> {
+  UpdateCustomTimetableEventParams params;
+
+  UpdateCustomTimetableEvent(this.params) : super('server/timetable/customEvents');
+
+  @override
+  void assemble(String raw) {}
+
+  @override
+  Future<Response>? request(Uri uri) {
+    return http.patch(uri, body: jsonEncode(params.toJson()));
+  }
+
+}