Feature: Min-relative entropy for quantum channels

[vprusso]

Implement a function that calculates the min-relative entropy for quantum channels.

The functionality for this should be created in channel_props/min_relative_entropy.py with corresponding unit tests found in tests/test_channel_props/test_min_relative_entropy.py. Be sure to also update the docs in /docs/channels.rst under "Properties of Quantum Channels" with toqito.channel_props.min_relative_entropy.py.

For a definition of min-relative entropy for quantum channels, consult:
https://arxiv.org/abs/1907.06306

See related tasks:
Min-relative entropy (quantum states): #40
Max-relative entropy (quantum states): #41
Max-relative entropy (quantum channels): #43

[vprusso]

Closing as part of task clean-up.