* Fix issues with POSIX::Spawn, Terrapin and Ruby 3.0
Also improve the Terrapin monkey-patch for the stderr/stdout issue.
* Fix keyword argument handling throughout the codebase
* Monkey-patch Paperclip to fix keyword arguments handling in validators
* Change validation_extensions to please CodeClimate
* Bump microformats from 4.2.1 to 4.3.1
* Allow Ruby 3.0
* Add Ruby 3.0 test target to CircleCI
* Add test for admin dashboard warnings
* Fix admin dashboard warnings on Ruby 3.0
* Fix media processing getting stuck on too much stdin/stderr
See thoughtbot/terrapin#5
* Remove dependency on paperclip-av-transcoder gem
* Remove dependency on streamio-ffmpeg gem
* Disable stdin on ffmpeg process
