feat: add new CronTrigger task type

[zevaryx]

Pull Request Type

• Feature addition
• Bugfix
• Documentation update
• Code refactor
• Tests improvement
• CI/CD pipeline enhancement
• Other: [Replace with a description]

Description

Adds a new Task Trigger, CronTrigger. Pass a cron string to it (i.e. 0 0 * * *), and it'll run tasks based on that cron string

Changes

• Add croniter requirement
• Add CronTrigger task trigger

Related Issues

Test Scenarios

@Task.create(CronTrigger("* * * * *"))
async def test_cron(self) -> None:
    print("I run every minute!")

Python Compatibility

• I've ensured my code works on Python 3.10.x
• I've ensured my code works on Python 3.11.x

Checklist

• I've run the pre-commit code linter over all edited files
• I've tested my changes on supported Python versions
• I've added tests for my code, if applicable
• I've updated / added documentation, where applicable

[AstreaTSS]

This debatably solves #1560.

[silasary]

This debatably solves #1560.

I think it does, yeah

[AstreaTSS]

Don't know what's going on with the PR's diff, but looks fine otherwise.