The Boltzmann constant and Avogadro constant values are incorrect

[rwsmith7531]

The Boltzmann constant is defined incorrectly in unyt. In the revised SI, it is defined with an exact value of 1.380649e-23.

The Avogadro constant is likewise defined incorrectly in unyt according to the revised SI, which defines it as exactly 6.02214076e23. I also noticed that unyt.Na is equal to neither 1, 6.02214076e23, nor the erroneous conversion factor currently used by unyt. Furthermore the expression (1.0*unyt.Unit('')).to_value('1/mol') yields 6.02214129011674e+23, which is also different.

[chrishavlin]

There's a draft PR updating to CODATA 2022 that updates both of those: #590 not sure of its status.