Expand pub constraint on test_api (#615)

This package is not impacted by the breaking changes, and they are already
running together internally.

Prepare to publish.

This is necessary to unblock the package roll for the flutter repository.
https://github.com/flutter/flutter/pull/123350

PiperOrigin-RevId: 519012847
diff --git a/CHANGELOG.md b/CHANGELOG.md
index a08f8a6..53456ea 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 5.4.0-dev
+## 5.4.0
 
 * Fix nice mocks generation in mixed mode (generated code is pre null-safety,
   while mocked class is null-safe).
diff --git a/lib/src/version.dart b/lib/src/version.dart
index 8e2c41a..3dfd2c8 100644
--- a/lib/src/version.dart
+++ b/lib/src/version.dart
@@ -1 +1 @@
-const packageVersion = '5.4.0-dev';
+const packageVersion = '5.4.0';
diff --git a/pubspec.yaml b/pubspec.yaml
index b985795..060205f 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: mockito
-version: 5.4.0-dev
+version: 5.4.0
 description: >-
   A mock framework inspired by Mockito with APIs for Fakes, Mocks,
   behavior verification, and stubbing.
@@ -18,7 +18,7 @@
   meta: ^1.3.0
   path: ^1.8.0
   source_gen: '>=0.9.6 <2.0.0'
-  test_api: '>=0.2.1 <0.5.0'
+  test_api: '>=0.2.1 <0.6.0'
 
 dev_dependencies:
   build_runner: ^2.0.0