Update Go rules to 0.16.3 and Gazelle to 0.15.0.

Author: DrMarcII

WORKSPACE

@@ -35,19 +35,19 @@ http_archive(
 
 http_archive(
     name = "io_bazel_rules_go",
-    sha256 = "5f3b0304cdf0c505ec9e5b3c4fc4a87b5ca21b13d8ecc780c97df3d1809b9ce6",
+    sha256 = "b7a62250a3a73277ade0ce306d22f122365b513f5402222403e507f2f997d421",
     urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/0.15.1/rules_go-0.15.1.tar.gz",
-        "https://github.com/bazelbuild/rules_go/releases/download/0.15.1/rules_go-0.15.1.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/0.16.3/rules_go-0.16.3.tar.gz",
+        "https://github.com/bazelbuild/rules_go/releases/download/0.16.3/rules_go-0.16.3.tar.gz",
     ],
 )
 
 http_archive(
     name = "bazel_gazelle",
-    sha256 = "c0a5739d12c6d05b6c1ad56f2200cb0b57c5a70e03ebd2f7b87ce88cabf09c7b",
+    sha256 = "6e875ab4b6bf64a38c352887760f21203ab054676d9c1b274963907e0768740d",
     urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/bazel-gazelle/releases/download/0.14.0/bazel-gazelle-0.14.0.tar.gz",
-        "https://github.com/bazelbuild/bazel-gazelle/releases/download/0.14.0/bazel-gazelle-0.14.0.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-gazelle/releases/download/0.15.0/bazel-gazelle-0.15.0.tar.gz",
+        "https://github.com/bazelbuild/bazel-gazelle/releases/download/0.15.0/bazel-gazelle-0.15.0.tar.gz",
     ],
 )