fix: resolve 2 remaining strict analysis errors

- introPage.dart: Convert fireItems to proper static function closure
- mainDrawer.dart: Convert unreadCount int to String for Text widget

lib/attributionMapPlugin.dart

@@ -2,19 +2,19 @@ import 'package:flutter/material.dart';
 
 /// Attribution widget for displaying map attribution text
 class AttributionPluginWidget extends StatelessWidget {
-  final String text;
 
-  AttributionPluginWidget({this.text = ""});
+  const AttributionPluginWidget({super.key, this.text = ''});
+  final String text;
 
   @override
   Widget build(BuildContext context) {
-    var style = new TextStyle(
+    const TextStyle style = TextStyle(
       fontSize: 12.0,
       color: Colors.white,
     );
     return Padding(
       padding: const EdgeInsets.all(5.0),
-      child: new Text(
+      child: Text(
         text,
         style: style,
       ),