Fix latest semver tag retrieval for first time setup

[stefafafan]

I think tagpr v1.1.3 has a breaking change; when Songmu/tagpr is first setup, the Semver tag retrieval fails and returns "" .

For example, the hatenablog-workflows repository which already has some tags tried to setup tagpr but ended up with the following Pull Request:

• Release for v0.0.1 hatena/hatenablog-workflows#33
  • As you can see in the changelog, tapr mistakes the current version as v0.0.0 hatena/hatenablog-workflows@ac48399

This is probably because of #159 ; once you setup .tagpr file manually it works, but first time setup there is no .tagpr so latestSemverTag fails.

I attempted to fix the problem by adding a condition check; if the config is defined check the vPrefix, otherwise return the first value (v1.1.2 behavior).

Here is some example code to show what I want to do: https://go.dev/play/p/OgCCpuethSr

[Songmu]

Oops. Thank you!

[stefafafan]

Thanks for the quick merge! 😄

[k1LoW]

@stefafafan Thank you!!!

[stefafafan]

This fix works as intended, thanks again!
hatena/hatenablog-workflows#37