Abrahamson and Gulerce 2020: rhoB and rhoW are swapped in csv file

The rhoB and rhoW in AG20.csv are swapped compared to the tables in the PEER report (Table 5.4) and the EqSpectra paper (Electronic supplement Table E6). I assume the publications are correct.

changed the description

mentioned in merge request !423 (closed)

added Bug GMM labels

Cursory review of updated test results indicate this change affects sigma values in the 3rd or greater decimal place.

mentioned in merge request !430 (merged)

mentioned in commit e64879c7

closed with merge request !430 (merged)