add back needed register_toolchains

Author: alexeagle

MODULE.bazel

@@ -37,6 +37,9 @@ protoc = use_extension("@toolchains_protoc//protoc:extensions.bzl", "protoc")
 # Match protobuf above, until it ships a pre-built binary toolchain itself
 protoc.toolchain(version = "v29.3")
 
+use_repo(protoc, "toolchains_protoc_hub")
+
+register_toolchains("@toolchains_protoc_hub//:all")
 
 go_sdk = use_extension("@rules_go//go:extensions.bzl", "go_sdk")
 go_sdk.download(version = "1.24.0")