Remove POTCAR hash check

[Andrew-S-Rosen]

The POTCAR hash-based validity checking should be removed. Here are two open issues where this sentiment was raised:

https://github.com/materialsproject/pymatgen/issues/4467

I think this is really an unnecessary level of complexity and we should just kill off the hash check

https://github.com/materialsproject/pymatgen/issues/3956

I would suggest simply disabling the hash altogether.

I agree with the assessment and think that it causes undue anxiety for end users due to false warnings. Ultimately, if the warnings cannot be trusted, then they are no use at all. This part of the code should be excised altogether, but I had trouble doing so in my very quick initial attempt.