解决go mod或go get时`x509: certificate signed by unknown authority`错误

通常go get私有仓库时会出现以下错误：

go: xxx@v0.0.0-20190918102752-bb51b27911ca: unrecognized import path "xxx" (https fetch: Get https://xxx?go-get=1: x509: certificate signed by unknown authority)

缘由是go get的执行过程须要https证书，检查server端证书是未知CA签署的并报错。

• 解决方法:
  go get -insecure xxx 这样go get就会经过http协议去访问私库了。