Gallerist

- Adds Python 3.10 to the build matrix and classifiers
- Upgrades dependencies

- Completely migrates to GitHub Workflows
- Adds a changelog
- Improves badges
- Upgrades to new versions of `Pillow` and `aiofiles`
- Improves formatting

- Completely migrates to GitHub Workflows
- Adds a changelog
- Improves badges
- Upgrades to new version of `gallerist` (which includes upgraded `Pillow` and
`aiofiles`), and to the new version of `azure-storage-blob`
[(v12)](https://docs.microsoft.com/en-us/azure/storage/blobs/storage-quickstart-blobs-python)
- Improves formatting


Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).