Rev package versions for release.
Rev package versions for release.

sky_engine is now at 0.0.45
sky_services is now at 0.0.45
flx is now at 0.0.4
flutter is now at 0.0.15
flutter_sprites is now at 0.0.12

spritewidget/spritewidget,spritewidget/spritewidget,spritewidget/spritewidget