Log Message:
Update to prettyprinter-1.7.1

* Deprecate the Data.Text.Prettyprint.* modules
  * Users should migrate to the new Prettyprinter module hierarchy.
  * The old modules will be removed no sooner than September 2022.
* Make text an optional dependency:
  * When built with -f-text, any text-based APIs will operate on Strings
    instead.
* Documentation improvements:
  * #194
  * 1f0bffe