Take absolute value for magnetic moment validation

[munrojm]

Ensures the absolute value of the magnetic moments is taken when doing validation

[codecov-commenter]

Codecov Report

Merging #415 (b1ba786) into main (9369cd2) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##             main     #415   +/-   ##
=======================================
  Coverage   98.08%   98.08%           
=======================================
  Files         109      109           
  Lines       23194    23194           
=======================================
  Hits        22749    22749           
  Misses        445      445           

Impacted Files	Coverage Δ
emmet-core/emmet/core/vasp/validation.py	82.17% <0.00%> (ø)

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