[Python] Release 0.53.0

Fixed

• Draft 4 type: integer matching a float or not depending on its repr; a float is never a draft 4 integer.
• Draft 4 type: integer accepting Decimal("1E+2").
• uniqueItems accepting 0 alongside -0.0 in arrays of more than 15 items.

Performance

• Canonicalizing an allOf of object schemas walks their property maps once instead of looking every key up.
• properties and required compare short names without memcmp.
• type: integer, and type sets containing it, are up to 67x faster on float-heavy instances.
• Draft 4 type: integer is up to 20x faster on float-heavy instances.
• Raising ValidationError is up to 38% faster.
• evaluate is up to 30% faster, from rendering each node's locations once.
• Building a schema resolves each $ref target once instead of per reference site.
• Building a schema with an $id encodes each absolute location once instead of re-validating it.
• enum listing strings or integers, with or without null, matches against a set instead of comparing each candidate.