Change format of git tags so the library is go module aware

[m90]

If you currently install the package in a Go 1.11 module aware environment, the existing git tags will be ignored as they are expected to start with a v, i.e. 3.0.0 should be v3.0.0 instead: https://github.com/golang/go/wiki/Modules#modules

Is it possible to start tagging the releases in this way, so that it can be properly consumed as a module as well?

[suzuki-shunsuke]

Thank you for the issue!
I have created tags started with "v".
https://github.com/line/line-bot-sdk-go/tags

And we will created tags started with "v" from the next time.

Thank you again.

[m90]

Thanks, I'm already consuming the tagged version!