Bump firebase_crashlytics from 3.0.9 to 3.3.7

Bumps [firebase_crashlytics](https://github.com/firebase/flutterfire/tree/master/packages/firebase_crashlytics) from 3.0.9 to 3.3.7.
- [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_crashlytics-v3.3.7/packages/firebase_crashlytics)

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

Signed-off-by: dependabot[bot] <[email protected]>