[palette_generator] Remove unmanaged code snippet (#7962)

Simplifies the README so that it no longer uses a code snippet, as the snippet was not adding any value over pub.dev instructions, and removes it from the code-excerpt exclusion list.

Part of flutter/flutter#102679

Author: stuartmorgan-g

packages/palette_generator/CHANGELOG.md

@@ -1,5 +1,6 @@
-## NEXT
+## 0.3.3+5
 
+* Updates README to link to the published example.
 * Updates minimum supported SDK version to Flutter 3.19/Dart 3.3.
 
 ## 0.3.3+4

packages/palette_generator/README.md

@@ -7,11 +7,5 @@ find colors for a user interface.
 
 ## Example
 
-Import the library via
-
-```dart
-import 'package:palette_generator/palette_generator.dart';
-```
-
-Then use the `PaletteGenerator` Dart class in your code. To see how this is done,
-check out the [image_colors example app](example/).
+To see how to use the `PaletteGenerator` class in your code, see
+[the example app](https://pub.dev/packages/palette_generator/example).

packages/palette_generator/pubspec.yaml

@@ -2,7 +2,7 @@ name: palette_generator
 description: Flutter package for generating palette colors from a source image.
 repository: https://github.com./flutter/packages/tree/main/packages/palette_generator
 issue_tracker: https://github.com./flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+palette_generator%22
-version: 0.3.3+4
+version: 0.3.3+5
 
 environment:
   sdk: ^3.3.0

script/configs/temp_exclude_excerpt.yaml

@@ -7,6 +7,5 @@
 # https://github.com./flutter/flutter/issues/102679
 - espresso
 - in_app_purchase/in_app_purchase
-- palette_generator
 - pointer_interceptor
 - quick_actions/quick_actions