revert to an assertion value of 0.57 in the function test_run_ppmi_lsa_pipeline
revert to an assertion value of 0.57 in the function test_run_ppmi_lsa_pipeline

Based on this comment -> https://xcs224u-scpd.slack.com/archives/CTD43MFUJ/p1582832331041400
cgpotts/cs224u