update dockerfile and appveyor.yml

.circleci/images/primary/Dockerfile

@@ -1,5 +1,5 @@
 # FROM golang:1.10.1
-FROM golang:1.16.5-stretch AS build
+FROM golang:1.16.6-stretch AS build
 # FROM govgo/go:1.11.1
 
 RUN apt update && apt install -y --no-install-recommends \

appveyor.yml

@@ -34,7 +34,7 @@ environment:
       PATH: C:\msys64\mingw32\bin\;C:\Program Files (x86)\NSIS\;%PATH%
   # - COMPILER: MINGW_W64
   #   ARCHITECTURE: x64
-  GOVERSION: 1.16.5
+  GOVERSION: 1.16.6
   # GOPATH: c:\gopath
 
 # scripts that run after cloning repository