pw_env_setup: Update go version to 1.16.3

Change-Id: I534aa2eed35c6ab64c2966e19fafca12623ac277
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/43581
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Reviewed-by: Alexei Frolov <frolv@google.com>
Reviewed-by: Joe Ethier <jethier@google.com>
diff --git a/pw_build/go.gni b/pw_build/go.gni
index ce84061..3434883 100644
--- a/pw_build/go.gni
+++ b/pw_build/go.gni
@@ -122,7 +122,10 @@
     program = "go"
     args = [ "get" ]
     deps = [ ":$_deps_metadata_target_name" ] + invoker.deps
-    env = [ "GOPATH=$_default_gopath" ]
+    env = [
+      "GO111MODULE=off",
+      "GOPATH=$_default_gopath",
+    ]
     args_file = _deps_metadata_file
 
     # If the args file is empty, don't run the "go get" command.
@@ -145,7 +148,10 @@
       ":$_download_target_name",
       ":$_metadata_target_name",
     ]
-    env = [ "GOPATH+=$_default_gopath" ]
+    env = [
+      "GO111MODULE=off",
+      "GOPATH+=$_default_gopath",
+    ]
     env_file = _metadata_file
 
     _binary_name = get_path_info(invoker.package, "name")
diff --git a/pw_env_setup/py/pw_env_setup/cipd_setup/pigweed.json b/pw_env_setup/py/pw_env_setup/cipd_setup/pigweed.json
index aabc647..137eae9 100644
--- a/pw_env_setup/py/pw_env_setup/cipd_setup/pigweed.json
+++ b/pw_env_setup/py/pw_env_setup/cipd_setup/pigweed.json
@@ -57,9 +57,9 @@
     ]
   },
   {
-    "path": "infra/go/${os}-${arch=amd64}",
+    "path": "infra/3pp/tools/go/${platform}",
     "tags": [
-      "version:1.13.5"
+      "version:2@1.16.3"
     ]
   },
   {