v5.31.0

This release adds support for MongoDB 🎉 as requested in #544 and #539. The documentation describes how to get started.
The MongoDB entity set supports read, update, create, delete, and query operations, and has extensive support for filters on an attached MongoDB collection.

This release also includes better support for open types. Previously open types were available, but were not flagged in the OData metadata, and rejecting the insertion of undeclared properties into non-open types was not enforced.