[pigeon] Update analyzer version (#10352)

Adds compatibility with version 8 of the `analyzer` package. I did not update to version 9 of the `analyzer` directly, because I think it's sensible to adopt 8 and have a release of pigeon that conforms to 8 first. This will give the chance to consuming projects to upgrade analyzer versions at their own pace. As as follow up PR, I can also work on updating to version 9 for a future release.

Fixes flutter/flutter#175432

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Author: dgyurov

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 26.0.4
+
+* Adds compatibility with `analyzer` 8.x.
+
 ## 26.0.3
 
 * [kotlin] Removes all `containsKey` and replaces with `contains`.

packages/pigeon/lib/src/generator_tools.dart

@@ -15,7 +15,7 @@ import 'generator.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '26.0.3';
+const String pigeonVersion = '26.0.4';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/pubspec.yaml

@@ -2,13 +2,13 @@ name: pigeon
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 repository: https://github.com/flutter/packages/tree/main/packages/pigeon
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+pigeon%22
-version: 26.0.3 # This must match the version in lib/src/generator_tools.dart
+version: 26.0.4 # This must match the version in lib/src/generator_tools.dart
 
 environment:
   sdk: ^3.7.0
 
 dependencies:
-  analyzer: ">=6.0.0 <8.0.0"
+  analyzer: ">=6.0.0 <9.0.0"
   args: ^2.1.0
   code_builder: ^4.10.0
   collection: ^1.15.0