Bump firebase_core and cloud_firestore in /flutter_maps_firestore (#1484)

Bumps [firebase_core](https://github.com/firebase/flutterfire/tree/master/packages/firebase_core) and [cloud_firestore](https://github.com/firebase/flutterfire/tree/master/packages/cloud_firestore). These dependencies needed to be updated together.

Updates `firebase_core` from 1.24.0 to 2.0.0
- [Release notes](https://github.com/firebase/flutterfire/releases)
- [Changelog](https://github.com/firebase/flutterfire/blob/master/CHANGELOG.md)
- [Commits](https://github.com/firebase/flutterfire/commits/firebase_core_web-v2.0.0/packages/firebase_core)

Updates `cloud_firestore` from 3.5.1 to 4.0.1
- [Release notes](https://github.com/firebase/flutterfire/releases)
- [Changelog](https://github.com/firebase/flutterfire/blob/master/CHANGELOG.md)
- [Commits](https://github.com/firebase/flutterfire/commits/cloud_firestore-v4.0.1/packages/cloud_firestore)

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

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

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

flutter_maps_firestore/pubspec.yaml

@@ -8,8 +8,8 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
-  cloud_firestore: ^3.1.10
-  firebase_core: ^1.2.0
+  cloud_firestore: ">=3.1.10 <5.0.0"
+  firebase_core: ">=1.2.0 <3.0.0"
   google_maps_flutter: ^2.0.0
   google_maps_webservice: ^0.0.20-nullsafety.0
   location: ^4.0.0-nullsafety.0