Update Go to 1.16.7

go1.16.7 (released 2021-08-05) includes a security fix to the net/http/httputil
package, as well as bug fixes to the compiler, the linker, the runtime, the go
command, and the net/http package. See the Go 1.16.7 milestone on the issue
tracker for details:

https://github.com/golang/go/issues?q=milestone%3AGo1.16.7+label%3ACherryPickApproved

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

script/setup/prepare_env_windows.ps1

@@ -1,6 +1,6 @@
 # Prepare windows environment for building and running containerd tests
 
-$PACKAGES= @{ mingw = ""; git = ""; golang = "1.16.6"; make = "" }
+$PACKAGES= @{ mingw = ""; git = ""; golang = "1.16.7"; make = "" }
 
 write-host "Downloading chocolatey package"
 curl.exe -L "https://packages.chocolatey.org/chocolatey.0.10.15.nupkg" -o 'c:\choco.zip'