v0.52.0

Return error for all invocations of protoc-gen-buf-check-breaking and protoc-gen-buf-check-lint.

As one of the few changes buf will ever make, protoc-gen-buf-check-breaking and protoc-gen-buf-check-lint were deprecated and scheduled for removal for v1.0 in January 2021. In preparation for v1.0, instead of just printing out a message notifying users of this, these commands now return an error for every invocation and will be completely removed when v1.0 is released.

The only migration necessary is to change your installation and invocation from protoc-gen-buf-check-breaking to protoc-gen-buf-breaking andprotoc-gen-buf-check-lint to protoc-gen-buf-lint. These can be installed in the exact same manner, whether from GitHub Releases, Homebrew, AUR, or direct Go installation:

# instead of go get github.com/bufbuild/buf/cmd/protoc-gen-buf-check-breaking
go get github.com/bufbuild/buf/cmd/protoc-gen-buf-breaking
# instead of curl -sSL https://github.com/bufbuild/buf/releases/download/v0.52.0/protoc-gen-buf-check-breaking-Linux-x86_64
curl -sSL https://github.com/bufbuild/buf/releases/download/v0.52.0/protoc-gen-buf-breaking-Linux-x86_64

There is no change in functionality.