Issue 1 add vtimezone

[niccokunzmann]

Description of change

This fixes #1.
Based on fix: niccokunzmann/x-wr-timezone#22

Pull-Request Checklist

• Code is up-to-date with the main branch
• [c] This pull request follows the contributing guidelines.
• This pull request links relevant issues as Fixes #0000
• There are new or updated unit tests validating the change
• Documentation has been updated to reflect this change
• The new commits follow conventions outlined in the conventional commit spec, such as "fix(api): prevent racing of requests".

• If pre-commit.ci is failing, try pre-commit run -a for further information.
• If CI / test is failing, try uv run pytest for further information.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
src/mergecal/calendar_merger.py	95.45% <100.00%> (+10.60%)	⬆️

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[niccokunzmann]

Thanks!

Also have a look at this if you like tests: niccokunzmann/open-web-calendar#629