无法正确安装指定的版本

[hongsheng@sh]

Describe the bug
通过go install方式安装指定版本时，始终都会自动安装最新的版本，例如：

[dev@dev bin]$ go install github.com/zhufuyi/sponge/cmd/sponge@1.8.0
go: github.com/zhufuyi/sponge/cmd/sponge@1.8.0: github.com/zhufuyi/sponge/cmd/sponge@1.8.0: invalid version: unknown revision 1.8.0
[dev@dev bin]$ go install github.com/zhufuyi/sponge/cmd/sponge@v1.8.0
go: downloading github.com/zhufuyi/sponge v1.8.0
go: downloading github.com/huandu/xstrings v1.3.3
[dev@dev bin]$ sponge -v
sponge version v1.8.1

Environments (please complete the following information):

• OS: CentOS Linux 7 (Core)
• sponge version 1.8.0

More description
none

[zhuyasen]

可以更新到指定版本，例如 sponge upgrade --version=v1.7.0