Update Go to 1.16.8

This includes additional fixes for CVE-2021-39293.

go1.16.8 (released 2021-09-09) includes a security fix to the archive/zip package,
as well as bug fixes to the archive/zip, go/internal/gccgoimporter, html/template,
net/http, and runtime/pprof packages. See the Go 1.16.8 milestone on the issue
tracker for details:

https://github.com/golang/go/issues?q=milestone%3AGo1.16.8+label%3ACherryPickApproved

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
diff --git a/Dockerfile b/Dockerfile
index 0a9e142..f269457 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,7 +3,7 @@
 ARG CROSS="false"
 ARG SYSTEMD="false"
 # IMPORTANT: When updating this please note that stdlib archive/tar pkg is vendored
-ARG GO_VERSION=1.16.7
+ARG GO_VERSION=1.16.8
 ARG DEBIAN_FRONTEND=noninteractive
 ARG VPNKIT_VERSION=0.5.0
 ARG DOCKER_BUILDTAGS="apparmor seccomp"
diff --git a/Dockerfile.e2e b/Dockerfile.e2e
index f73f639..abf4289 100644
--- a/Dockerfile.e2e
+++ b/Dockerfile.e2e
@@ -1,4 +1,4 @@
-ARG GO_VERSION=1.16.7
+ARG GO_VERSION=1.16.8
 
 FROM golang:${GO_VERSION}-alpine AS base
 ENV GO111MODULE=off
diff --git a/Dockerfile.simple b/Dockerfile.simple
index ac04616..c1e247f 100644
--- a/Dockerfile.simple
+++ b/Dockerfile.simple
@@ -5,7 +5,7 @@
 
 # This represents the bare minimum required to build and test Docker.
 
-ARG GO_VERSION=1.16.7
+ARG GO_VERSION=1.16.8
 
 FROM golang:${GO_VERSION}-buster
 ENV GO111MODULE=off
diff --git a/Dockerfile.windows b/Dockerfile.windows
index 7e1ae96..30cf370 100644
--- a/Dockerfile.windows
+++ b/Dockerfile.windows
@@ -165,7 +165,7 @@
 # Use PowerShell as the default shell
 SHELL ["powershell", "-Command", "$ErrorActionPreference = 'Stop'; $ProgressPreference = 'SilentlyContinue';"]
 
-ARG GO_VERSION=1.16.7
+ARG GO_VERSION=1.16.8
 ARG GOTESTSUM_COMMIT=v0.5.3
 
 # Environment variable notes: