sebtrack

Updated to latest, string unix timestamp is not understood by 'get'

3

## Issue Description ```python import arrow arrow.get('1657831049') ``` results in ``` arrow.parser.ParserError: Could not match input '1657831049' to any of the following formats: YYYY-MM-DD, YYYY-M-DD, YYYY-M-D, YYYY/MM/DD, YYYY/M/DD, YYYY/M/D, YYYY.MM.DD,...

I noticed that there are assert statements that are catched wrongly, if an assert statement fails it throws an `AssertionError` not `ValueError` nor `KeyError`. https://github.com/kLabUM/rrcf/blob/34504c14bba233f86a7dcae35d55fc84cc5b7508/rrcf/rrcf.py#L429-L438 Also consider removing all assert...