uofgravity/glasflow: v0.4.0

Release of glasflow v0.4.0. Added Add various autoregressive flows using the existing transforms in nflows (https://github.com/uofgravity/glasflow/pull/62) Add scale_activation keyword argument to nflows.transforms.autoregressive.MaskedAffineAutoregressiveTransform (https://github.com/uofgravity/nflows/pull/11) Changed Drop support for Python 3.7 (https://github.com/uofgravity/glasflow/pull/61) Full Changelog: https://github.com/uofgravity/glasflow/compare/v0.3.1...v0.4.0