Update firebase_core (#273)

Author: epou

pubspec.yaml

@@ -24,7 +24,7 @@ dependencies:
   flutter_image_compress: ^2.3.0
   flutter_markdown: ^0.7.4+3
   firebase_messaging: ^15.2.0
-  firebase_core: ^3.10.0
+  firebase_core: ^3.12.1
   auto_size_text: ^3.0.0
   file_picker: ^8.0.3
   device_info_plus: ^9.1.2