feat: added Software Licenses screen (fossasia#2697)

Author: Vidhijain20

lib/constants.dart

@@ -132,3 +132,4 @@ List<String> connectWithUs = [
   'Watch us on Youtube',
   'Developers'
 ];
+String softwareLicenses = 'Software Licenses';

lib/main.dart

@@ -8,6 +8,7 @@ import 'package:pslab/view/instruments_screen.dart';
 import 'package:pslab/view/oscilloscope_screen.dart';
 import 'package:pslab/view/settings_screen.dart';
 import 'package:pslab/view/about_us_screen.dart';
+import 'package:pslab/view/software_licenses_screen.dart';
 
 import 'constants.dart';
 
@@ -47,6 +48,7 @@ class MyApp extends StatelessWidget {
         '/faq': (context) => const FAQScreen(),
         '/settings': (context) => const SettingsScreen(),
         '/aboutUs': (context) => const AboutUsScreen(),
+        '/softwareLicenses': (context) => const SoftwareLicensesScreen(),
       },
     );
   }