Bump firebase_core from 1.15.0 to 1.16.0 in /experimental/web_dashboard (#1214)

Bumps [firebase_core](https://github.com/FirebaseExtended/flutterfire) from 1.15.0 to 1.16.0.
- [Release notes](https://github.com/FirebaseExtended/flutterfire/releases)
- [Changelog](https://github.com/firebase/flutterfire/blob/master/CHANGELOG.md)
- [Commits](https://github.com/FirebaseExtended/flutterfire/compare/firebase_core-v1.15.0...firebase_core_v1.16.0)

---
updated-dependencies:
- dependency-name: firebase_core
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

experimental/web_dashboard/pubspec.lock

@@ -245,7 +245,7 @@ packages:
       name: firebase_core
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.15.0"
+    version: "1.16.0"
   firebase_core_platform_interface:
     dependency: transitive
     description: