KAT-58: changed the import name into circulation.dart (lower case)

rescueapp/lib/start_triage_system/breathing_frequency_per_minute.dart

 import 'package:flutter/material.dart';
-import 'Circulation.dart';
+import 'circulation.dart';
 
 class BreathingFrequencyPerMinute extends StatefulWidget {
   BreathingFrequencyPerMinute({Key key, this.title}) : super(key: key);