[google_sign_in_ios] Move pigeon as a dev dependency (#5685)

Fixes: https://github.com/flutter/flutter/issues/140213

packages/google_sign_in/google_sign_in_ios/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 5.7.1
+
+* Changes `pigeon` to a dev dependency.
+
 ## 5.7.0
 
 * Adds support for macOS.

packages/google_sign_in/google_sign_in_ios/pubspec.yaml

@@ -2,7 +2,7 @@ name: google_sign_in_ios
 description: iOS implementation of the google_sign_in plugin.
 repository: https://github.com/flutter/packages/tree/main/packages/google_sign_in/google_sign_in_ios
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+google_sign_in%22
-version: 5.7.0
+version: 5.7.1
 
 environment:
   sdk: ">=3.2.0 <4.0.0"
@@ -25,7 +25,6 @@ dependencies:
   flutter:
     sdk: flutter
   google_sign_in_platform_interface: ^2.2.0
-  pigeon: ^11.0.1
 
 dev_dependencies:
   build_runner: ^2.4.6
@@ -34,6 +33,7 @@ dev_dependencies:
   integration_test:
     sdk: flutter
   mockito: 5.4.3
+  pigeon: ^11.0.1
 
 topics:
   - authentication