Update icalendar requirement from <5.1,>=4.0.3 to >=6.3.2,<6.4

[dependabot]

Updates the requirements on icalendar to permit the latest version.

Release notes

Sourced from icalendar's releases.

v6.3.2

To view the changes, please see the Changelog. This release can be installed from PyPI.

Changelog

Sourced from icalendar's changelog.

6.3.2 (2025-11-03)

Minor changes

- Add PyData Theme version switcher to documentation. See :issue:`825`.
5.0.14 (2025-11-03)
Minor changes

• Add PyData Theme version switcher to documentation. See :issue:825.

4.1.2 (2025-11-03)

Minor changes

- Add PyData Theme version switcher to documentation. See :issue:`825`.
7.0.0a1 (28-10-2025)
Minor changes

• Split up cal.py into different files as sub-package.
• Format more source code with ruff.
• Exclude type checking block from test coverage.
• Add private icalendar.compatibility module to merge functionality for older Python versions into one place.
• Add type annotation to from_ical().
• Fix enum documentation.
• DTSTAMP, LAST_MODIFIED, and CREATED can now be set to None to delete the value.
• Enhanced Calendar.new() to support organization and language parameters for automatic PRODID generation.
• Added duration setter to Event class for more intuitive event creation.
• Added validate() method to Calendar class for explicit validation of required properties and components.
• Add improved setters for start, duration, and end properties with explicit locking mechanisms to provide more flexible property manipulation while maintaining RFC 5545 compliance. The implementation includes comprehensive test coverage to ensure proper behavior and backward compatibility.
• Add new() method to vCalAddress class for consistent API usage. The method supports all RFC 5545 parameters including CN, CUTYPE, DELEGATED-FROM, DELEGATED-TO, DIR, LANGUAGE, PARTSTAT, ROLE, RSVP, and SENT-BY, with automatic mailto: prefix handling. See :issue:870.
• Refactor set_duration methods in Event and Todo classes to eliminate code duplication by extracting common logic into shared set_duration_with_locking() function in icalendar.attr. See :issue:886.
• Consolidate duplicate logic patterns between Event and Todo classes by extracting shared functions in icalendar.attr for property setters, validation logic, and property access. This eliminates approximately 150 lines of duplicate code while maintaining 100% backward compatibility and RFC 5545 compliance. See :issue:891.
• Accept and ignore non-standard empty RDATE fields when parsing ICS files.
• Improve contributing documentation by adding a change log requirement, adding a pull request template, adding clear CI enforcement warnings, and updating README.rst. See :issue:890.
• Make coverage submission optional for CI.
• Bump actions/setup-python version from 5 to 6 for CI.
• Add comment explaining tzdata dependency purpose to prevent confusion. See :issue:900.
• Fix duplicate blank issue template by adding config.yml to disable GitHub's default blank option. See :issue:777.

... (truncated)

Commits

• 51f017e Follow PyData Sphinx Theme's conf.py example to fiddle with RTD and dev ver...
• 2f0683a Release v6.3.2
• 19dc99f Update JSON URL
• 3b964fa Show the version warning banner
• ece7f0b Shorten title to make version switcher fit
• edd3bc7 Cut 6.x branch and build docs with version switcher.
• 29e13c4 Merge pull request #851 from niccokunzmann/release
• e253a7f version 6.3.1
• c1835ac Merge pull request #850 from niccokunzmann/issue-836
• 7e8abb5 Make the parser escape certain characters
• Additional commits viewable in compare view

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