title: Firebase_auth depends on firebase_core error
body: <p>cloud_firestore: ^0.14.4
  firebase_auth: ^0.18.4+1
  smooth_star_rating: ^1.0.4
  geopoint: ^0.7.1
  geoflutterfire: ^2.2.1
  google_maps: ^4.0.0
  firebase_core: ^0.7.0</p>
  <p>Because firebase_auth 0.18.4+1 depends on firebase_core ^0.5.3 and no versions of firebase_auth match &gt;0.18.4+1 &lt;0.19.0, firebase_auth ^0.18.4+1 requires firebase_core ^0.5.3.
  So, because app_name depends on both firebase_auth ^0.18.4+1 and firebase_core ^0.7.0, version solving failed.</p>
  <p>pub get failed (1; So, because app_name depends on both firebase_auth ^0.18.4+1 and firebase_core ^0.7.0, version solving failed.)
  exit code 1</p>