v4.0.0

• Partial support for Draft 2020-12 (as well as 2019-09).
  Thanks to Thomas Schmidt and Harald Nezbeda.
• False and 0 are now properly considered non-equal even
  recursively within a container (#686). As part of this change,
  uniqueItems validation may be slower in some cases. Please feel
  free to report any significant performance regressions, though in
  some cases they may be difficult to address given the specification
  requirement.
• The CLI has been improved, and in particular now supports a --output
  option (with plain (default) or pretty arguments) to control the
  output format. Future work may add additional machine-parsable output
  formats.
• Code surrounding DEFAULT_TYPES and the legacy mechanism for
  specifying types to validators have been removed, as per the deprecation
  policy. Validators should use the TypeChecker object to customize
  the set of Python types corresponding to JSON Schema types.
• Validation errors now have a json_path attribute, describing their
  location in JSON path format
• Support for the IP address and domain name formats has been improved
• Support for Python 2 has been dropped, with python_requires properly
  set.
• multipleOf could overflow when given sufficiently large numbers. Now,
  when an overflow occurs, jsonschema will fall back to using fraction
  division (#746).
• jsonschema.__version__, jsonschema.validators.validators,
  jsonschema.validators.meta_schemas and
  jsonschema.RefResolver.in_scope have been deprecated, as has
  passing a second-argument schema to Validator.iter_errors and
  Validator.is_valid.