v0.2.1

• Removal of rpy2 dependency for improved compatibility across systems
• Use GSEApy as backend for GSEA and ssGSEA
• Minor syntax changes
  • ora.ttest_res is now ora.DA_test_res (as we can implement t-test or MWU tests)
  • sspa_fgsea() is now sspa_gsea() and uses gseapy as the backend rather than R fgsea
  • sspa_gsva() is temporarily deprecated due to the need for the rpy2 compatability - use the GSVA R package