Updating dependencies

Hi,

thank you for your excellent starter template.
Unfortunately, I have problems resolving the dependencies or updating the packages. Especially with the Firebase packages, there are now many improvements. Can you provide an updated version?

`Because firebase_auth >=0.18.4 <=0.18.4 depends on firebase_auth_web ^0.3.2+2 and firebase_auth ^0.18.4+1 depends on firebase_auth_web ^0.3.2+3, firebase_auth ^0.18.4 requires firebase_auth_web ^0.3.2+2.
And because no versions of firebase_auth match >0.18.3+1 <0.18.4 and firebase_auth 0.18.3+1 depends on firebase_auth_web ^0.3.2+1, firebase_auth ^0.18.3+1 requires firebase_auth_web ^0.3.2+1.
And because firebase_auth_web >=0.3.0-dev.1 <0.4.0-1.0.nullsafety.0 depends on intl ^0.16.1 and every version of flutter_localizations from sdk depends on intl 0.17.0, firebase_auth ^0.18.3+1 is incompatible with flutter_localizations from sdk.
So, because firebasestarter depends on both flutter_localizations any from sdk and firebase_auth ^0.18.3+1, version solving failed.
pub get failed (1; So, because firebasestarter depends on both flutter_localizations any from sdk and firebase_auth ^0.18.3+1, version solving failed.)
Process finished with exit code 1`

Easy upgrading to all current or dev versions of all packages is not successful.

Best regards

No file, test, or entry point is named. Start by reproducing the reported `pub get` failure and inspect the project's dependency declarations, especially the Flutter Firebase packages and their `intl` constraints. Done means the dependencies resolve successfully with compatible current versions.

Written by the indexing model from the issue text.