Updated firebase and dart sdk (#198)

Co-authored-by: Mikael Wills <[email protected]>

Author: mikaelwills

example/pubspec.yaml

@@ -7,7 +7,7 @@ version: 0.1.1
 publish_to: "none" # Remove this line if you wish to publish to pub.dev
 
 environment:
-  sdk: ">=2.12.2 <3.19.0"
+  sdk: ">=2.12.2 <4.0.0"
 
 dependencies:
   callkeep:
@@ -18,14 +18,14 @@ dependencies:
     # the parent directory to use the current plugin's version.
     path: ../
 
-  firebase_messaging: ^14.9.2
+  firebase_messaging: ^15.2.0
   flutter:
     sdk: flutter
   logger: ^2.0.2+1
   uuid: ^4.4.0
 
 dev_dependencies:
-  flutter_lints: ^2.0.1
+  flutter_lints: ^5.0.0
   flutter_test:
     sdk: flutter
 

pubspec.yaml

@@ -4,11 +4,11 @@ version: 0.4.0
 homepage: https://github.com/flutter-webrtc/callkeep
 
 environment:
-  sdk: ">=2.12.0 <3.0.0"
+  sdk: ">=2.12.0 <4.0.0"
   flutter: ">=1.22.0"
 
 dependencies:
-  firebase_messaging: ^14.9.2
+  firebase_messaging: ^15.2.0
   flutter:
     sdk: flutter
   logger: ^2.0.2+1
@@ -17,7 +17,6 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  pedantic: ^1.9.0
 
 flutter:
   plugin: