fix: Preserve explicit signs for years when combined with decades

[serhii73]

When both decades and years are present (e.g. '-1 decade +2 years'), the code in get_kwargs() unconditionally overwrote explicit_signs['years'] with the decades sign value:

if 'decades' in explicit_signs:
    explicit_signs['years'] = explicit_signs['decades']

This destroyed the user-supplied +/- that was recorded for years during the PATTERN match loop, causing _parse_date() to mishandle the sign of the merged years value.

Fix: only propagate the decades sign to years when years did not carry its own explicit sign (explicit_signs.get('years') is False/absent).

Regression tests added for:

• '-1 decade' (only decades, negative)
• '-1 decade 2 years' (decades negative, years implicit)
• '-1 decade +2 years' (decades negative, years explicitly positive)
• '+2 years' (only years, explicitly positive future)
• '1 decade +2 years' (decades implicit, years explicitly positive)
• '+1 decade -2 years' (decades explicitly positive, years explicitly negative)

Fixes #1304

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.10%. Comparing base (373ede9) to head (d06a1d5).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1330   +/-   ##
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  Coverage   97.10%   97.10%           
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  Files         235      235           
  Lines        2904     2904           
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  Hits         2820     2820           
  Misses         84       84           

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[Copilot]

Pull request overview

Fixes a sign-handling bug in the freshness/relative-date parser where combining decades and years could overwrite an explicitly provided sign on years (e.g. -1 decade +2 years), leading to incorrect direction when computing the final relative delta.

Changes:

• Update FreshnessDateDataParser.get_kwargs() to only propagate the decades explicit-sign flag to years when years does not already have its own explicit sign.
• Add regression tests covering mixed-sign and explicit-sign combinations for decades+years (and standalone explicitly-signed years).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
dateparser/freshness_date_parser.py	Preserves an explicit +/- on years when merging decades into years, preventing incorrect sign inversion.
tests/test_freshness_date_parser.py	Adds regression coverage for the decades+years explicit-sign interaction, including mixed-sign cases.

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[AdrianAtZyte]

Shouldn’t the expectation be 12 here?

[wRAR]

I also wasn't sure about this.