feat: allow to use .PreviousTag on templates

[caarlos0]

Previous tag will be available as a template field. It will be empty if there are no previous tag (e.g. first ever release of a repo).

Changelog still works by using the first commit on those cases (as it already does today).

refs #2669

[caarlos0]

one problem with this: on the first tag, this will actually be a commit... 🤔 which per-se is not that bad, its just that the name will not convey what it actually is at some point 🤔

[codecov]

Codecov Report

Merging #2683 (b06be12) into main (419b6fc) will increase coverage by 0.01%.
The diff coverage is 85.00%.

@@            Coverage Diff             @@
##             main    #2683      +/-   ##
==========================================
+ Coverage   84.76%   84.77%   +0.01%     
==========================================
  Files         103      103              
  Lines        7883     7890       +7     
==========================================
+ Hits         6682     6689       +7     
  Misses        985      985              
  Partials      216      216              

Impacted Files	Coverage Δ
pkg/context/context.go	100.00% <ø> (ø)
internal/pipe/changelog/changelog.go	91.21% <62.50%> (-0.19%)	⬇️
internal/pipe/git/git.go	87.97% <100.00%> (+0.89%)	⬆️
internal/tmpl/tmpl.go	97.56% <100.00%> (+0.01%)	⬆️

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[blacktop]

👍

[blacktop]

one problem with this: on the first tag, this will actually be a commit... 🤔 which per-se is not that bad, its just that the name will not convey what it actually is at some point 🤔

Maybe a default v0.0.0 would make sense? I tried v0.0.0 and a commit hash in github's URL and both 404ed (I know that is not the only purpose of this feature, however. I kinda feel like a zero-ed out version would make more sense than a commit hash?

[blacktop]

I'm not intimately familiar with your code, but everything looked good to me. 👍

[caarlos0]

Maybe a default v0.0.0 would make sense? I tried v0.0.0 and a commit hash in github's URL and both 404ed (I know that is not the only purpose of this feature, however. I kinda feel like a zero-ed out version would make more sense than a commit hash?

my comment was outdated, it will now be empty as stated in the docs... which makes sense, as if there is no previous tag, that's what I would expect...

[dirien]

LGTM 👍🏻