Use the "new" platform syntax to declare web support

https://dart.dev/tools/pub/pubspec#platforms

pana would not mark web as supported, because some dart:io imports are found (all covered with if (kIsWeb) checks)

pubspec.yaml

@@ -44,6 +44,14 @@ dev_dependencies:
   test: ^1.21.0
   transparent_image: ^2.0.0
 
+platforms:
+  android:
+  ios:
+  linux:
+  macos:
+  web:
+  windows:
+
 flutter:
   assets:
     - packages/wiredash/assets/images/logo_white.png