chore: attempt fixes for failing builds for beta, and dev versions of Flutter

Author: danvick

packages/flutter_form_builder/lib/src/fields/form_builder_text_field.dart

@@ -184,7 +184,7 @@ class FormBuilderTextField extends FormBuilderField<String> {
   ///
   /// This setting is only honored on iOS devices.
   ///
-  /// If unset, defaults to the brightness of [ThemeData.primaryColorBrightness].
+  /// If unset, defaults to the theme brightness.
   final Brightness? keyboardAppearance;
 
   /// {@macro flutter.widgets.editableText.scrollPadding}

packages/form_builder_extra_fields/example/android/app/build.gradle

@@ -26,7 +26,7 @@ apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 30
+    compileSdkVersion 31
 
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'

packages/form_builder_validators/example/android/app/build.gradle

@@ -26,7 +26,7 @@ apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 30
+    compileSdkVersion 31
 
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'