Update environment dependency to support up to Dart v3

pubspec.yaml

@@ -1,14 +1,13 @@
 name: event_bus
 version: 2.0.1
-author: Marco Jakob <[email protected]>
 description: A simple Event Bus using Dart Streams for decoupling applications
 repository: https://github.com/marcojakob/dart-event-bus
 homepage: https://code.makery.ch/library/dart-event-bus/
 environment:
   sdk: '>=2.12.0 <4.0.0'
 dev_dependencies:
-  build_runner: ^1.2.5
-  build_web_compilers: ^2.16.4
-  build_test: ^1.3.7
+  build_runner: ^2.0.0
+  build_web_compilers: ^3.0.0
+  build_test: ^2.0.0
   logging: ^1.0.0
   test: ^1.5.0