fix validate action

lib/presentation/screens/actions/harvest_process/sc_edit_action_harvest_process.dart

@@ -174,7 +174,6 @@ class _EditActionHarvestProcessScreenState
                   _harvestProcess.harvestId = newValue.id;
                 });
               },
-              validator: (value) => value == null ? "Mã thu hoạch" : null,
               isExpanded: true,
               items: _buildDropMenu(_harvests));
         } else {

lib/presentation/screens/actions/packing/sc_edit_action_packing.dart

@@ -160,7 +160,6 @@ class _EditActionPackingScreenState extends State<EditActionPackingScreen> {
                   _packing.harvestId = newValue.id;
                 });
               },
-              validator: (value) => value == null ? "Mã thu hoạch" : null,
               isExpanded: true,
               items: _buildDropMenu(_harvests));
         } else {

lib/presentation/screens/actions/sell/sc_edit_action_sell.dart

@@ -160,7 +160,6 @@ class _EditActionSellScreenState extends State<EditActionSellScreen> {
                   _sell.harvestId = newValue.id;
                 });
               },
-              validator: (value) => value == null ? "Mã thu hoạch" : null,
               isExpanded: true,
               items: _buildDropMenu(_harvests));
         } else {