Improve compatibility with Elixir 1.19

Fix functions for required fields to skip fields with nillable types

Improve compatibility with Elixir 1.18

Allow for more recent nimble_parsec versions (#32)

* Allow for more recent nimble_parsec versions
* Allow latest dependencies for projects with Elixir > 12

---------

Co-authored-by: Ivan Rublev <ivan@ivanrublev.me>

Support sum type as an element of the list type

Fix ecto validate_required warning

Increase compatibility with Elixir 1.15 and OTP 26

Clean deps from unloadable modules (#27)

* Clean deps from unloadable modules

* Fix calling not running resolve planner

* Add acceptance test of passing without crash on dependency removal

* Bump version to 1.5.12

* Add praises

---------

Co-authored-by: Stefan Schulze <stefan.andre.schulze@posteo.de>
Co-authored-by: Ivan Rublev <ivan@ivanrublev.me>

Improve compatibility wiht ElixirLS