Update WORKSPACE for rules_proto v6

WORKSPACE

@@ -1,5 +1,14 @@
 workspace(name = "grpc_ecosystem_grpc_gateway")
 
+http_archive(
+    name = "bazel_features",
+    sha256 = "95fb3cfd11466b4cad6565e3647a76f89886d875556a4b827c021525cb2482bb",
+    strip_prefix = "bazel_features-1.10.0",
+    url = "https://github.com/bazel-contrib/bazel_features/releases/download/v1.10.0/bazel_features-v1.10.0.tar.gz",
+)
+load("@bazel_features//:deps.bzl", "bazel_features_deps")
+bazel_features_deps()
+
 load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
@@ -55,10 +64,12 @@ http_archive(
     ],
 )
 
-load("@rules_proto//proto:repositories.bzl", "rules_proto_dependencies", "rules_proto_toolchains")
+load("@rules_proto//proto:repositories.bzl", "rules_proto_dependencies")
 
 rules_proto_dependencies()
 
+load("@rules_proto//proto:toolchains.bzl", "rules_proto_toolchains")
+
 rules_proto_toolchains()
 
 http_archive(