Python 3.13 support

[waza-ari]

Your package is being used in other libraries (for example Taskiq), which do support Python 3.13.

When installing those libraries on Python 3.13, they resolve to pycron version 3.0.0, because newer pycron versions specify Python version constraints, while older ones do not. This leads to situations like this, where the version constraints theoretically allow an update, but the Python version constraints do not:

$ poetry update
Updating dependencies
Resolving dependencies... (2.2s)

No dependencies to install or update

$ poetry show -o                                                  
pycron    3.0.0  3.1.1  Simple cron-like parser, which determines if current datetime matches conditions.

$ poetry show --why --tree pycron   
taskiq 0.11.10 Distributed task queue with full async support
└── pycron >=3.0.0,<4.0.0

I'm preparing a Merge Request to add Python 3.13 support to pycron. There is a dependency which doesn't have Python 3.13 support either, therefore I'm adding this issue here for tracking, which can be picked up once TheKevJames/coveralls-python#549 is resolved.

[kipe]

I think we could just drop coveralls-python, as it doesn't seem to be that well maintained. We could just require 100 % test coverage in the tests instead, then coveralls is more or less useless anyways.

[waza-ari]

Hey, sounds good to me. Was looking through their repo and found it to be somewhat abandoned. Removing coveralls would probably also mean dropping the badge in the Readme, are you fine with that?