add Bolin number formulae

[AgnieszkaZaba]

addresses #1662
(clean version of previous PR)

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 85.67%. Comparing base (156f86c) to head (fedd2db).

Files with missing lines	Patch %	Lines
...physics/isotope_relaxation_timescale/bolin_1958.py	66.66%	1 Missing ⚠️
...physics/isotope_relaxation_timescale/zaba_et_al.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1669      +/-   ##
==========================================
- Coverage   85.68%   85.67%   -0.02%     
==========================================
  Files         405      405              
  Lines        9790     9796       +6     
==========================================
+ Hits         8389     8393       +4     
- Misses       1401     1403       +2     

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[slayoo]

suggest moving to trivia as:

def tau(Bo, dm_dt_over_m):
   ...