Upgrade google_maps package version to 7.1.0

[zolboo-gtn]

Can not used with google_maps_flutter.
google_maps_flutter@latest depends on google_maps@7.1.0 while this package is on google_maps@6.1.0.

[liorboyango]

I updated my fork with latest dependencies, including google_maps 7.1.0:

flutter_google_street_view:
   git:
      url: https://github.com/liorboyango/flutter_street_view.git
      path: flutter_google_street_view
      ref: master