Release 0.2.1 with fixes for proto package

[djmarcin]

Release 0.2.0 seems broken when using the proto packages. #1241 fixed this but needs a release package to be built.

[UebelAndre]

Seems reasonable to me. I've opened #1243 and am just waiting for concurrence from the other maintainers.

[UebelAndre]

This is done.
https://github.com/bazelbuild/rules_rust/releases/tag/0.2.1