Update Go to 1.16.6 (cont.)

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

Author: AkihiroSuda

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

@@ -2,7 +2,7 @@
   become: yes
   roles:
   - role: config-golang
-    go_version: '1.16.3'
+    go_version: '1.16.6'
     arch: arm64
   tasks:
   - name: Install pre-requisites

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

@@ -2,7 +2,7 @@
   become: yes
   roles:
   - role: config-golang
-    go_version: '1.16.3'
+    go_version: '1.16.6'
     arch: arm64
   tasks:
   - name: Build and test containerd