Dialogy

- [x] update: WER calibration refactored to contain core logic.
- [x] update: **Deprecated** post-processors and pre-processors.
- [x] feat: trainable plugins.
- [x] update: **Drop support for python 3.7**

- [x] update: WER calibration as a plugin.

- [x] add: WER calibration. This plugin can eliminate ASR alternatives if acoustic model and language model scores are available.

- [x] add: Template migration `dialogy update <project>`.
- [x] add: `DucklingPlugin` tracks network issues and optionally returns entities collected till failure.

- [x] [fix](https://github.com/Vernacular-ai/dialogy/issues/60): Entity scoring within `EntityExtractor` and `DucklingPlugin`.
- [x] [fix](https://github.com/Vernacular-ai/dialogy/issues/58): CurrencyEntity added to operate on `amount-of-money` dimension.
- [x] add: TimeIntervalEntities sometimes may contain a hybrid structure that resembles some values as `TimeEntities`.

- [x] add: `KeywordEntity` entity-type class.
- [x] refactor: `ListEntityPlugin` doesn't need an entity map. Uses `KeywordEntity` instead.
- [x] refactor: **breaking** All plugins are now available under: `dialogy.plugins`.
- [x] refactor: `Workflow` can be serialized.