chore: update reference from next to main

Author: Lyokone

pubspec.yaml

@@ -43,12 +43,12 @@ dependencies:
   dart_firebase_admin:
     git:
       url: https://github.com/invertase/dart_firebase_admin.git
-      ref: next
+      ref: main
       path: packages/dart_firebase_admin
   google_cloud_firestore:
     git:
       url: https://github.com/invertase/dart_firebase_admin.git
-      ref: next
+      ref: main
       path: packages/google_cloud_firestore
   stack_trace: ^1.12.1
   protobuf: ^6.0.0
@@ -75,5 +75,5 @@ dependency_overrides:
   google_cloud_firestore:
     git:
       url: https://github.com/invertase/dart_firebase_admin.git
-      ref: next
+      ref: main
       path: packages/google_cloud_firestore