Update Bazel Go dependencies

WORKSPACE

@@ -7,27 +7,27 @@ load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
 
 http_archive(
     name = "io_bazel_rules_go",
-    sha256 = "7b9bbe3ea1fccb46dcfa6c3f3e29ba7ec740d8733370e21cdc8937467b4a4349",
+    sha256 = "7904dbecbaffd068651916dce77ff3437679f9d20e1a7956bff43826e7645fcc",
     urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/v0.22.4/rules_go-v0.22.4.tar.gz",
-        "https://github.com/bazelbuild/rules_go/releases/download/v0.22.4/rules_go-v0.22.4.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/v0.25.1/rules_go-v0.25.1.tar.gz",
+        "https://github.com/bazelbuild/rules_go/releases/download/v0.25.1/rules_go-v0.25.1.tar.gz",
     ],
 )
 
 load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_dependencies")
 
 go_rules_dependencies()
 
-go_register_toolchains()
+go_register_toolchains(version = "1.15.6")
 
 # Import Gazelle
 
 http_archive(
     name = "bazel_gazelle",
-    sha256 = "d8c45ee70ec39a57e7a05e5027c32b1576cc7f16d9dd37135b0eddde45cf1b10",
+    sha256 = "222e49f034ca7a1d1231422cdb67066b885819885c356673cb1f72f748a3c9d4",
     urls = [
-        "https://storage.googleapis.com/bazel-mirror/github.com/bazelbuild/bazel-gazelle/releases/download/v0.20.0/bazel-gazelle-v0.20.0.tar.gz",
-        "https://github.com/bazelbuild/bazel-gazelle/releases/download/v0.20.0/bazel-gazelle-v0.20.0.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-gazelle/releases/download/v0.22.3/bazel-gazelle-v0.22.3.tar.gz",
+        "https://github.com/bazelbuild/bazel-gazelle/releases/download/v0.22.3/bazel-gazelle-v0.22.3.tar.gz",
     ],
 )
 
@@ -44,9 +44,9 @@ go_repositories()
 
 http_archive(
     name = "com_google_protobuf",
-    sha256 = "758249b537abba2f21ebc2d02555bf080917f0f2f88f4cbe2903e0e28c4187ed",
-    strip_prefix = "protobuf-3.10.0",
-    urls = ["https://github.com/protocolbuffers/protobuf/archive/v3.10.0.tar.gz"],
+    sha256 = "9748c0d90e54ea09e5e75fb7fac16edce15d2028d4356f32211cfa3c0e956564",
+    strip_prefix = "protobuf-3.11.4",
+    urls = ["https://github.com/protocolbuffers/protobuf/archive/v3.11.4.zip"],
 )
 
 load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
@@ -55,12 +55,11 @@ protobuf_deps()
 
 # rules_docker
 
-# TODO(leo): We need the Python 3 fixes in master to run on RHEL/CentOS 8 and recent Fedora versions.
-# Revert to release later.
-git_repository(
+http_archive(
     name = "io_bazel_rules_docker",
-    commit = "166b6bc2856f62dd263b1e7635f3a331dc325230",
-    remote = "https://github.com/bazelbuild/rules_docker",
+    sha256 = "1698624e878b0607052ae6131aa216d45ebb63871ec497f26c67455b34119c80",
+    strip_prefix = "rules_docker-0.15.0",
+    urls = ["https://github.com/bazelbuild/rules_docker/releases/download/v0.15.0/rules_docker-v0.15.0.tar.gz"],
 )
 
 load(