message: fix a compile error of r2.1 caused by skylib address invalid.
diff: @@ -67,7 +67,7 @@ http_archive(
  http_archive(
  name = "bazel_skylib",
  sha256 = "1dde365491125a3db70731e25658dfdd3bc5dbdfd11b840b3e987ecf043c7ca0",
  - urls = ["https://github.com/bazelbuild/bazel-skylib/releases/download/0.9.0/bazel-skylib.0.9.0.tar.gz"],
  + urls = ["https://github.com/bazelbuild/bazel-skylib/releases/download/0.9.0/bazel_skylib-0.9.0.tar.gz"],
  ) # https://github.com/bazelbuild/bazel-skylib/releases
  http_archive(
  name = "com_github_apple_swift_swift_protobuf",
  