Updates for RAIL, cleaning up dependencies, fixes for scipy 1.8

What's Changed

• Switch to numpy dict for writing ensembles by @eacharles in #60
• remove explicit astropy dependence by @eacharles in #62
• Issue/58/iterator by @sschmidt23 in #63
• Added handling of multi-dimensions and quadratic quantile interpolation by @eacharles in #64
• fix notebooks by @eacharles in #68
• add objdata to dict passed to get_allocation_kwds by @sschmidt23 in #70
• fixes for scipy changes in pdf() amd cdf() functions by @eacharles in #74

Full Changelog: v0.4...v0.5