Release 0.173.0

Defect fixes:

• Fixed issue #473 about bigint and -Werror=stringop-overflow

• Fixed jmespath issue #471 about jmespath::search and ojson with AddressSanitizer in macos environment

• Fixed jsonpointer issue with json_pointer::parse for empty string keys (which had implications
  for jsonschema definitions keyword with empty keys.)

• Fixed jsonschema issue with definitions keyword with empty keys

• Fixed jsonschema issue #474 about JSON Schema maximum keyword error message

• Fixed jsonschema issue with multipleOf keyword and type integer and multipleOf a floating point number

• Fixed jsonschema issue with the behavior of $id for rebasing in some keywords, particularly if, then, and else.

Enhancements:

• The jsonschema::make_schema functions now support providing a retrieval URI, to initialize the base URI.