Test source distributions outside the checkout

[ryux1]

Linked issue

• Closes [Bug] missing files for tests #1708

Description

Source distributions omitted generate_windows_to_olson_mapping.py, so two tests shipped in the archive failed outside a repository checkout. This includes the required file and adds an isolated CI job that downloads, unpacks, and tests the built source archive. Release jobs now depend on that test.

The isolated source-distribution result changes from two failures to a passing suite. After rebasing onto the current main, the full checkout suite passes with 18,382 tests, 24 skips, and 526 expected failures.

Checklist

• I added a change log entry, following the instructions in all subsections under Change log requirements.
• I followed icalendar's Artificial intelligence policy and disclosed my Responsible AI use in my commit messages, if applicable.
• I added or updated tests, if applicable.
• I ran and ensured all tests pass locally by following Run tests.
• I added or edited documentation as necessary, both as docstrings to be rendered in the API documentation and narrative documentation, following the Style guide.

Prepared with OpenAI Codex assistance. The contributor's personal review, responsibility, and understanding attestation remains pending; the PR will stay in draft until that is complete.

[github-actions]

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[github-actions]

Profile summary:

GitHub user: ryux1
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GitHub user: ryux1
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   🟢 Profile information:
        name: Ryu
        company: Earth
        location: Solar System,
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          const ryu={role:"Systems architect",focus:"Networks+Scale",guard:"Integrity+Stability",exec:()=> "precision"}
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   51 PRs opened in the last 21 days.
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   4 new issues opened in the last 21 days.
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[coveralls-official]

coverage: 97.568%. remained the same — ryux1:fix/1708-test-built-packages into collective:main

[read-the-docs-community]

Documentation build overview

📚 icalendar | 🛠️ Build #34441699 | 📁 Comparing bb465df against latest (2e55d6e)

  🔍 Preview build  

9 files changed · ± 9 modified

± Modified

• genindex.html
• _modules/icalendar/attr.html
• reference/api/icalendar.cal.alarm.html
• reference/api/icalendar.cal.availability.html
• reference/api/icalendar.cal.available.html
• reference/api/icalendar.cal.component.html
• reference/api/icalendar.cal.event.html
• reference/api/icalendar.cal.todo.html
• _modules/icalendar/cal/component.html