Publish version 3.0.0

[derekxu16]

The Dart SDK has a check that ensures that dependency constraints in our packages are compatible with the versions of packages pulled in by the DEPS file. The version of package:protobuf in DEPS is 3.0.0-dev, but there is no published version of package:protobuf 3.0.0. This means that the check is currently stopping us from using both package:protobuf: ^2.0.0 and package:protobuf: ^3.0.0 as constraints in our packages. Publishing package:protobuf 3.0.0 would fix this.

See https://dart-review.googlesource.com/c/sdk/+/303022/comment/d77751a4_f9e8fea8/ for more details.

[a-siva]

//cc @osa1

[sigurdm]

You can use protobuf: ^3.0.0-dev as a constraint. Or, if you are not affected by breaking changes between 2 and 3 protobuf: >=2.0.0 <4.0.0.

[osa1]

We just released protobuf-3.0.0 and protoc_plugin-21.0.0.