* 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
The cache store is explicitly used by some specs, but they were not
isolated and therefore not reliable. This fixes the issue by clearing
the cache after each specs.
