Built-in codec for NaiveDateTime.t().
Encodes NaiveDateTime structs to ISO 8601 strings without an offset
(e.g. "2023-04-01T12:30:00") and decodes them back. Handles :json and
:binary_string formats (returning a binary string) and :string format
(returning a charlist).
The schema is a string with a pattern, not format: "date-time": JSON
Schema's date-time format requires an offset, which a NaiveDateTime lacks.
Registration
Registered automatically when the :spectral application starts. To use a
different codec for NaiveDateTime.t(), set it in config :spectra, :codecs;
user-configured codecs take precedence over the built-ins.