Update United States holidays: Alaska state holidays correction

[PPsyrius]

Proposed change

According to the "Alaska Dispatch":

The changing of the colors and the guard is commemorated in Alaska each Oct. 18, designated "Alaska Day," an official state holiday in 1917 by the third Territorial Legislature. That same year, territorial lawmakers also created Seward's Day, also a state holiday, to mark on each final Monday in March the signing of the purchase treaty.

Thus, the start date for this should be 1917 instead of 1867 as in the current implementation.

As for Seward's Day, a local newspaper mentioned that this wasn't observed in 1921:

Note

There's currently 2 state-level checks being used in United States test files at the moment, between

self.assertNoHolidayName(name, self.state_hols["AK"], range(1865, 1917))

and

self.assertNoHolidayName(name, UnitedStates(subdiv="AK", years=range(1865, 1917)))

with negligible performance difference between the two - though we should probably standardize our test code to either one of them.

Type of change

• 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/pin/upgrade)
• Bugfix (non-breaking change which fixes an issue)
• Breaking change (a code change causing existing functionality to break)
• New feature (new holidays functionality in general)

Checklist

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (4ff5d29) to head (bc92e08).
Report is 2 commits behind head on dev.

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files          191       191           
  Lines        11546     11546           
  Branches      1743      1743           
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  Hits         11546     11546           

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[KJhellico]

There's currently 2 state-level checks being used in United States test files at the moment, between

self.assertNoHolidayName(name, self.state_hols["AK"], range(1865, 1917))

and

self.assertNoHolidayName(name, UnitedStates(subdiv="AK", years=range(1865, 1917)))

But option with UnitedStates(subdiv= is used only for cases with observed=False or for years before 1865.

[KJhellico]

LGTM.

[arkid15r]

Could you include the relevant sources into the code?

// I've clarified the contributing instructions as they weren't clear on how it should be done.

[arkid15r]

👍 looks great!

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud