解決go mod或go get時`x509: certificate signed by unknown authority`錯誤

通常go get私有倉庫時會出現以下錯誤：

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)

緣由是go get的執行過程須要https證書，檢查server端證書是未知CA簽署的並報錯。

• 解決方法:
  go get -insecure xxx 這樣go get就會經過http協議去訪問私庫了。