feat(bump): add support to bumping local version

[marcossantiago]

Description

This PR creates adds a new flag --local-version to the bump command that allows bumping the local version only instead of the public release.

PS: I haven't create the tests/updated the documentation just yet. will do after confirmation the code is suitable.

Checklist

• Add test cases to all the changes you introduce
• Run ./script/format and ./script/test locally to ensure this change passes linter check and test
• Test the changes on the local machine manually
• Update the documentation for the changes

Expected behavior

The current behavior of the bump ignores the local version and only bumps the public version.

$ cz bump --files-only --yes
bump: version 2.6.0+3.0.0 → 2.7.0

This flag allows to bump only the local portion of the version like

$ cz bump --files-only --yes --local-version
bump: version 2.6.0+3.0.0 → 2.6.0+4.0.0

Steps to Test This Pull Request

1. Specify the version with a local portion like version = "5.6.0+0.0.1".
2. Execute the bump with the flag --local-version.

Additional context

Issue: #302
References: Python 440 Local version

[codecov]

Codecov Report

Merging #303 (720befe) into master (0be6d0b) will increase coverage by 0.34%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #303      +/-   ##
==========================================
+ Coverage   96.62%   96.96%   +0.34%     
==========================================
  Files          33       33              
  Lines         919      924       +5     
==========================================
+ Hits          888      896       +8     
+ Misses         31       28       -3     

Flag	Coverage Δ
unittests	96.96% <100.00%> (+0.34%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
commitizen/cli.py	97.36% <ø> (ø)
commitizen/commands/init.py	91.30% <ø> (ø)
commitizen/defaults.py	100.00% <ø> (ø)
commitizen/__version__.py	100.00% <100.00%> (ø)
commitizen/commands/bump.py	94.31% <100.00%> (+3.72%)	⬆️
commitizen/commands/changelog.py	97.29% <100.00%> (ø)
commitizen/git.py	95.55% <100.00%> (+0.04%)	⬆️
commitizen/cz/base.py	100.00% <0.00%> (ø)

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[Lee-W]

Could you please add a test for this change?

[marcossantiago]

Sure! Doing shortly.

[marcossantiago]

@Lee-W here it goes.

[Lee-W]

Only one typo need to be fixed. Other parts looks good to me 🎉 @woile Could you please double check whether everything's good 🙂

[woile]

Fantastic, thanks!