Add Seychelles holidays

[PPsyrius]

Proposed change

Add Seychelles holidays (en_SC, en_US).

Closes #1267.

[!NOTE] There's an incomplete list of Seychellois Creole crs translations for holiday names available at https://web.archive.org/web/20240312083508/https://seychellen.com/en/public-holidays/ for future improvement should we decide to implement them at a later date.

Type of change

• [x] New country/market holidays support (thank you!)
• [ ] Supported country/market holidays update (calendar discrepancy fix, localization)
• [ ] Existing code/documentation/test/process quality improvement (best practice, cleanup, refactoring, optimization)
• [ ] Dependency update (version deprecation/upgrade)
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] Breaking change (a code change causing existing functionality to break)
• [ ] New feature (new python-holidays functionality in general)

Checklist

• [x] I've followed the contributing guidelines
• [x] I've run make pre-commit, it didn't generate any changes
• [x] I've run make test, all tests passed locally

[coveralls]

Pull Request Test Coverage Report for Build 8249288462

Details

• 47 of 47 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 8235619848:	0.0%
Covered Lines:	10678
Relevant Lines:	10678

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💛 - Coveralls

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud