2.5.2
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* Allow unit values to be declared in the unit system through aliases and not just the base unit name.
* Fix some deprecations in tests and CI.

2.5.1
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* Get rid of most memoizations in favor of eager computations.

2.5.0
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* Add `CHANGELOG.md`.
* Fix some deprecations and warnings.
* Support Rails 6 and Ruby 2.6.
* Cache conversion table in JSON file for first load performance.