Update rmvtransport.py

[RexVizsla]

Hey, I wanted to get the departures at a specific time (f.e. "16:00") using the "time" flag which is supported by the RMV-API but not PyRMVtransport.
I changed the code of rmvtransport.py so that you're able to specify the time using
It works for me but it would be great if another person could double check that it works and there aren't any errors!

data = await rmv.get_departures(
                station_id=marburg_bahnhof,
                products=["RB","RE"],
                max_journeys=2,
                time="16:00")´´´
                

[cgtobi]

Thanks @RexVizsla for your contribution. Please run the pre-commit hooks to fix the CI complaints.

[user3287]

Danke Merkel