kishwarshafin/pepper: PEPPER-Margin-DeepVariant release r0.5

Updates in Oxford Nanopore variant calling in V0.5:

Reduce search space of PEPPER by only predicting on sites with variants Adding CNN layers on top of RNNs to improve predictions Remove PEPPER HP from the pipeline Support rows model for DeepVariant that uses alt alignment which significantly improves INDEL performance. Support for Guppy 5.0.7 and high-accuracy mode of Guppy.