0.6.3: Bugfixes, update docs

New Features

• add new method SchemaModel.to_yaml to serialize SchemaModels to yaml #428

Bugfixes

• preserve pandas extension types during validation (#443)
• Fix to_yaml serialization dropping global checks (#428) 🎉 first contribution @antonl 🎉
• fix empty data type not supported for serialization (#435)
• fix empty SchemaModel (#434)
• add doc about attributes excluded by SchemaModel (#436) @jeffzi
• fix DataFrameSchema comparison with non-DataFrameSchema (#431) @jeffzi
• schema serialization handles non-PandasDtype (#424)
• pa.Object coerce should preserve object type (#423)

Documentation

• Update documentation theme to use furo #444
• Add favicon e3540f1