remove psc as an option for standardising output

[htwangtw]

Closes #109

• leaving zscore the only behaviour so removing the parameter all together
• keep the method generator but just lock the standardize input

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.69%. Comparing base (b88333f) to head (0a74630).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #113      +/-   ##
==========================================
- Coverage   89.80%   89.69%   -0.11%     
==========================================
  Files          11       11              
  Lines         500      495       -5     
==========================================
- Hits          449      444       -5     
  Misses         51       51              

Files	Coverage Δ
giga_connectome/denoise.py	84.78% <ø> (ø)
giga_connectome/postprocess.py	86.56% <ø> (ø)
giga_connectome/run.py	96.42% <ø> (-0.13%)	⬇️
giga_connectome/utils.py	86.66% <ø> (-0.68%)	⬇️
giga_connectome/workflow.py	88.63% <100.00%> (ø)