Need testing for Solvent Select Commands

[teauxfu]

I only have access to MX-class pumps, which don't have the solvent select feature.
I would appreciate it if someone could test using the solvent property.

https://github.com/teauxfu/py-hplc/blob/26c872edddaa4d8b8c1b94e802f7ea3f5a7c3961/py_hplc/next_gen_pump.py#L317-L334