happa release v1.57.4

UISchema for Azure updated by @marians in https://github.com/giantswarm/happa/pull/4085
Visual improvements of the schema form added by @gusevda in https://github.com/giantswarm/happa/pull/4040, https://github.com/giantswarm/happa/pull/4053
Test cases added for schema using subschemas and oneOf, anyOf, not by @marians in https://github.com/giantswarm/happa/pull/4058
Schema form number field improvements added by @gusevda in https://github.com/giantswarm/happa/pull/4062
OpenStack schema removed by @kuosandys in https://github.com/giantswarm/happa/pull/4068
Validation errors improvements in schema form added by @kuosandys in https://github.com/giantswarm/happa/pull/4059
2020-12 draft support added by @gusevda in https://github.com/giantswarm/happa/pull/4079
Removing of empty objects and arrays from form fields while editing added by @kuosandys in https://github.com/giantswarm/happa/pull/4084
Multi-line string support and long titles/descriptions support added by @kuosandys in https://github.com/giantswarm/happa/pull/4095
Preprocessing of schema to handle oneOf and anyOf keywords added by @gusevda in https://github.com/giantswarm/happa/pull/4102

Full Changelog: https://github.com/giantswarm/happa/compare/v1.57.3...v1.57.4