cassava-megaparsec-2.0.0: CHANGELOG.md

## Cassava Megaparsec 2.0.0

* Works with Megaparsec 7.

## Cassava Megaparsec 1.0.0

* Works with Megaparsec 6.

* Instead of `Cec` we have `ConversionError` as custom component of error
  messages.

## Cassava Megaparsec 0.1.0

* Initial release.