fixed NUMBA_NUM_THREADS issue in ray multiprocessing (to match quimb …

[AlexisRalli]

…numba thread count)

[codecov-commenter]

Codecov Report

Merging #153 (ade0cf3) into main (e76d552) will not change coverage.
The diff coverage is 75.00%.

@@           Coverage Diff           @@
##             main     #153   +/-   ##
=======================================
  Coverage   77.32%   77.32%           
=======================================
  Files          33       33           
  Lines        3749     3749           
=======================================
  Hits         2899     2899           
  Misses        850      850           

Files Changed	Coverage Δ
symmer/utils.py	71.52% <50.00%> (ø)
symmer/operators/base.py	64.28% <100.00%> (-0.13%)	⬇️
symmer/operators/noncontextual_op.py	82.92% <100.00%> (ø)

... and 1 file with indirect coverage changes