General maintenance

• Add digest methods to PlatformImage class.
• Formally declare support for python 3.10.
• Bump minimum supported version of requests
• Fix some issues with the tests (type-checking and a broken assert statement).
• Add a shebang to the show script.

v1.1.0 - A bunch more niceties

• Export ImageHistoryItem through the package entrypoint.
• Add image_size property to PlatformImage and Manifest classes.
• Add short_digest property to all data classes that have a digest property. This is meant to mimic the short digests shown on Docker Hub.
• Add non_empty_history property to ImageConfig class, to retrieve a list of only non-empty layers. This is a convenience method to retrieve a list of history items that will nicely line up with the list of downloadable layers.
• Add clean_created_by property to ImageHistoryItem class, to centralise efforts for providing "nice" displays of layer information.

v1.0.2 - Packaging fix

Fixed a bug with the packaging + release process.

v1.0.1 - A few small niceties

• Declare support for Python 3.8
• Platform objects are now stringable
• Added wrapper method get_platform_images to Image class

v1.0.0 - First release after the fork

Major changes from upstream include:

• Complete removal of python2 support
• Complete removal of support for v1 registries
• A re-work of class names
• A re-work of the requests integration and registry auth service
• More higher-level abstractions, to avoid needing to dive into manifest dictionaries