[Python] Release 0.49.8

Performance

• Up to 380x faster canonicalization of a oneOf whose overlapping branches carry many properties, which no longer removes shared regions the exactly-one spelling discards.

Fixed

• Draft detection treating the version-less http://json-schema.org/schema meta-schema URI as a custom dialect, where it names the current draft.
• A patternProperties entry matching every key leaving additionalProperties: false spelled as a key constraint, where it forbids nothing.