* chore: update ash to use Ash.Type.Enum descriptions
Contextually, remove an unreachable clause that caused dyalizer to fail,
see https://github.com/ash-project/ash/pull/873 for the commit that made
it unreachable
* feat: allow providing descriptions for enum values
If the module exports `graphql_describe_enum_value/1`, use that. Otherwise,
fallback to the Ash.Type.Enum value descriptions introduced in
https://github.com/ash-project/ash/pull/940.
Close#116
