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>

.zuul/playbooks/containerd-build/integration-test.yaml

@@ -2,7 +2,7 @@
   become: yes
   roles:
   - role: config-golang
-    go_version: '1.16.3'
+    go_version: '1.16.7'
     arch: arm64
   tasks:
   - name: Install pre-requisites

.zuul/playbooks/containerd-build/run.yaml

@@ -2,7 +2,7 @@
   become: yes
   roles:
   - role: config-golang
-    go_version: '1.16.6'
+    go_version: '1.16.7'
     arch: arm64
   tasks:
   - name: Build containerd

.zuul/playbooks/containerd-build/unit-test.yaml

@@ -2,7 +2,7 @@
   become: yes
   roles:
   - role: config-golang
-    go_version: '1.16.3'
+    go_version: '1.16.7'
     arch: arm64
   tasks:
   - name: Build and test containerd