Icalendar

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Bug fixes:

- Fix vCategories for correct en/de coding.
[thet]

- vDuration property value: Fix changing duration sign after multiple ``to_ical`` calls.
Ref: 320
Fixes: 319
[barlik]

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Bug fixes:

- Support added for Python 3.9 and 3.10 (no code changes needed).

- Replace bare 'except:' with 'except Exception:' (281)

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Bug fixes:

- fixed rrule handling, re-enabled test_create_america_new_york()

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Bug fixes:

- Use ``vText`` as default type, when convert recurrence definition to ical string. [kam193]

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Bug fixes:

- Fixed a docs issue related to building on Read the Docs [davidfischer]

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Bug fixes:

- Reduce Hypothesis iterations to speed up testing, allowing PRs to pass
[UniversalSuperBox]