fix: add tzdata as a required dependency

[IzaakGough]

Summary

Fix scheduler test failures in environments that do not have timezone data installed by adding tzdata as a required dependency.

Problem/Root Cause

Issue #258 reports that test_on_schedule_call and test_on_schedule_decorator fail with ZoneInfoNotFoundError for America/Los_Angeles when the runtime environment does not have the tzdata package available.

The root cause is that the package relies on timezone data through Python's zoneinfo support, but tzdata was not listed in the project's required dependencies. That left installs dependent on environment-specific system timezone data being present.

Solution/Changes

Add tzdata>=2024.1 to the [project].dependencies list in pyproject.toml so timezone data is installed as part of the package's normal dependency set.

This removes the environment-specific dependency on preinstalled timezone data and ensures the scheduler code has access to the timezone definitions it needs in environments where system tzdata is missing.

Testing

• Manually verified that this patch ensures that both tests pass in the following MRE.

[gemini-code-assist]

Code Review

This pull request adds the 'tzdata' dependency to 'pyproject.toml'. The feedback recommends removing an unnecessary blank line introduced at the end of the 'dependencies' list to maintain clean formatting.