updated project style guidelines

lib/view/pages/timetable/customTimetableEventEditDialog.dart

@@ -51,8 +51,7 @@ class _AddCustomTimetableEventDialogState extends State<CustomTimetableEventEdit
   }
 
   @override
-  Widget build(BuildContext context) {
-    return AlertDialog(
+  Widget build(BuildContext context) => AlertDialog(
       insetPadding: const EdgeInsets.all(20),
       contentPadding: const EdgeInsets.all(10),
       title: const Text('Termin hinzufügen'),
@@ -89,7 +88,7 @@ class _AddCustomTimetableEventDialogState extends State<CustomTimetableEventEdit
               title: Text(Jiffy.parseFromDateTime(_date).yMMMd),
               subtitle: const Text('Datum'),
               onTap: () async {
-                final DateTime? pickedDate = await showDatePicker(
+                final pickedDate = await showDatePicker(
                   context: context,
                   initialDate: _date,
                   firstDate: DateTime.now().subtract(const Duration(days: 30)),
@@ -185,7 +184,7 @@ class _AddCustomTimetableEventDialogState extends State<CustomTimetableEventEdit
           onPressed: () {
             if(!validate()) return;
 
-            CustomTimetableEvent editedEvent = CustomTimetableEvent(
+            var editedEvent = CustomTimetableEvent(
               id: '',
               title: _eventName.text,
               description: _eventDescription.text,
@@ -231,5 +230,4 @@ class _AddCustomTimetableEventDialogState extends State<CustomTimetableEventEdit
         ),
       ],
     );
-  }
 }