Upgrade to Pydantic 1.9 to Support Delimiter Exclusion Via Model Config

[dixonwhitmire]

The upcoming Pydantic release, 1.9, will support adding export exclusions to Model Configuration class - pydantic/pydantic#660. This new feature will allow us to exclude the x12 "delimiters" from a model export using a single config.

This is an improvement over current functionality as we would need to exclude the delimiters in each "export" function ( dict(), json() etc) invocation.

[dixonwhitmire]

Insight on the upcoming pydantic release . The maintainer is an individual that's a bit time constrained at the moment.
pydantic/pydantic#3228

[dixonwhitmire]

Pydantic 1.9 is now available

[dixonwhitmire]

After reviewing the code it seems more appropriate to remove the delimiters from the X12Segment model, as they are metadata and not part of the data payload.

Changes include:

• Removing the delimiters field from the base segment model
• Adding a custom_delimiter parameter to the X12Segment.x12() method
• Updating the X12 segment group to support a delimiters attribute