chore(extra_fields): fix unnecessary import errors causing CI fails in beta and dev workflows

Author: danvick

packages/form_builder_extra_fields/lib/src/fields/form_builder_color_picker.dart

@@ -1,7 +1,5 @@
 import 'dart:async';
-import 'dart:ui';
 
-import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_colorpicker/flutter_colorpicker.dart';

packages/form_builder_extra_fields/lib/src/fields/form_builder_rating_bar.dart

@@ -1,6 +1,4 @@
-import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_form_builder/flutter_form_builder.dart';
 import 'package:flutter_rating_bar/flutter_rating_bar.dart';
 

packages/form_builder_extra_fields/lib/src/fields/form_builder_searchable_dropdown.dart

@@ -1,9 +1,6 @@
-import 'dart:ui';
-
 import 'package:dropdown_search/dropdown_search.dart' as dropdown_search;
 import 'package:dropdown_search/dropdown_search.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_form_builder/flutter_form_builder.dart';
 
 /// Field for selecting value(s) from a searchable list

packages/form_builder_extra_fields/lib/src/fields/form_builder_signature_pad.dart

@@ -2,7 +2,6 @@ import 'dart:typed_data';
 
 import 'package:flutter/material.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_form_builder/flutter_form_builder.dart';
 import 'package:signature/signature.dart';
 

packages/form_builder_extra_fields/lib/src/fields/form_builder_touch_spin.dart

@@ -1,5 +1,4 @@
 import 'package:flutter/material.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_form_builder/flutter_form_builder.dart';
 import 'package:flutter_touch_spin/flutter_touch_spin.dart';
 import 'package:intl/intl.dart';

packages/form_builder_extra_fields/lib/src/fields/form_builder_typeahead.dart

@@ -1,5 +1,4 @@
 import 'package:flutter/material.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_form_builder/flutter_form_builder.dart';
 import 'package:flutter_typeahead/flutter_typeahead.dart';