Make CI green

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index f98fbd7..66eddb0 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -1,7 +1,20 @@
 workspace(name = "rules_proto")
 
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
 load("//proto:repositories.bzl", "rules_proto_dependencies", "rules_proto_toolchains")
-
 rules_proto_dependencies()
-
 rules_proto_toolchains()
+
+http_archive(
+    name = "bazel_toolchains",
+    sha256 = "dcb58e7e5f0b4da54c6c5f8ebc65e63fcfb37414466010cf82ceff912162296e",
+    strip_prefix = "bazel-toolchains-0.28.2",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/archive/0.28.2.tar.gz",
+        "https://github.com/bazelbuild/bazel-toolchains/archive/0.28.2.tar.gz",
+    ],
+)
+
+load("@bazel_toolchains//rules:rbe_repo.bzl", "rbe_autoconfig")
+rbe_autoconfig(name = "buildkite_config")

proto/private/dependencies.bzl

diff --git a/proto/private/dependencies.bzl b/proto/private/dependencies.bzl
index acf3b44..f9ab13e 100644
--- a/proto/private/dependencies.bzl
+++ b/proto/private/dependencies.bzl
@@ -14,9 +14,10 @@
 
 dependencies = {
     "bazel_skylib": {
-        "sha256": "2ef429f5d7ce7111263289644d233707dba35e39696377ebab8b0bc701f7818e",
+        "sha256": "9245b0549e88e356cd6a25bf79f97aa19332083890b7ac6481a2affb6ada9752",
+        "strip_prefix": "bazel-skylib-0.9.0",
         "urls": [
-            "https://github.com/bazelbuild/bazel-skylib/archive/0.8.0.tar.gz",
+            "https://github.com/bazelbuild/bazel-skylib/archive/0.9.0.tar.gz",
         ],
     },
     "com_google_protobuf": {