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* Move type annotations inline
* Use `functools.lru_cache` for looking up emoji by name with `get_emoji_by_name()`
* Move internal functions `get_emoji_unicode_dict()`, `get_aliases_unicode_dict()`, `_EMOJI_UNICODE` and `_ALIASES_UNICODE` to `testutils`
* Add type hints to tests
* Remove obsolete dev dependency `coveralls`