0.21.0

What's Changed

Different kinds of modernizations and fixes.

• Fix Python sandbox and test infrastructure
• Improve Nominatim reverse geocoding heuristics and corresponding tests
• Fix dependencies. Thanks, @MauritsDescamps.
• LDI: Fix data acquisition
• LDI: Fix forwarding to MQTT
• OpenAQ: Fix acquisition for certain records without geo information
• Improve project tooling, add CI, linter, and code formatter
• Sanitize code and prose with linters

Full Changelog: 0.20.2...0.21.0