refactor(deps): replace dirs_next with etcetera

[tessus]

Description

This changed replaces the crate dirs with etcetera. The dirs crate unfortunately still returns the ~/Library/... directories and does not follow the XDG standard on macOS (which is also a Unix system at its core).
The directories in ~/Library/... are supposed to be used by macOS GUI applications and not terminal apps.

However, the change still maintains backwards compat in case a config file is stored in ~/Library/Application Support/git-cliff.

Motivation and Context

see #1475

How Has This Been Tested?

• cargo test
• manual testing

Screenshots / Logs (if applicable)

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 (if applicable).
• I have formatted the code with rustfmt.
  • cargo +nightly fmt --all
• I checked the lints with clippy.
  • cargo clippy --tests --verbose -- -D warnings
• I have added tests to cover my changes.
• All new and existing tests passed.
  • cargo test

[codecov-commenter]

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.45%. Comparing base (39cd76e) to head (b259b75).

Files with missing lines	Patch %	Lines
git-cliff-core/src/config.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1477      +/-   ##
==========================================
+ Coverage   47.35%   47.45%   +0.10%     
==========================================
  Files          24       24              
  Lines        2131     2129       -2     
==========================================
+ Hits         1009     1010       +1     
+ Misses       1122     1119       -3     

Flag	Coverage Δ
unit-tests	47.45% <50.00%> (+0.10%)	⬆️

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[orhun]

thx!