refactor(lib): unify serde and serde_derive using derive feature

[tranzystorekk]

Description

Makes serde usage more unified across the project thanks to the derive feature

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (no code change)
• Refactor (refactoring production code)
• Other

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov-commenter]

Codecov Report

Merging #57 (1543161) into main (848d8a5) will increase coverage by 0.26%.
The diff coverage is 12.50%.

@@            Coverage Diff             @@
##             main      #57      +/-   ##
==========================================
+ Coverage   41.14%   41.39%   +0.26%     
==========================================
  Files          13       13              
  Lines         812      807       -5     
  Branches      210      210              
==========================================
  Hits          334      334              
+ Misses        371      364       -7     
- Partials      107      109       +2     

Impacted Files	Coverage Δ
git-cliff-core/src/config.rs	24.45% <0.00%> (ø)
git-cliff-core/src/release.rs	14.29% <0.00%> (-10.71%)	⬇️
git-cliff-core/src/commit.rs	72.90% <50.00%> (ø)
git-cliff-core/src/repo.rs	29.17% <0.00%> (+2.09%)	⬆️

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[orhun]

Good thinking, thanks! 🐻