[Rust] Release 0.57.0

Added

• PreparedDocument::unsatisfiable, naming the keywords that leave each unsatisfiable subschema empty and where they are.

Changed

• PreparedDocument::unsatisfiable_pointers is replaced by PreparedDocument::unsatisfiable.

Fixed

• The instance path of a schema build error, which was empty instead of naming the keyword location that failed to compile.
• PreparedDocument::unsatisfiable_pointers passed over a subschema that admits no value only once its references resolve, such as an allOf over two $refs.

Performance

• Canonicalizing several subschemas of one prepared document parses each definition body once for the document instead of once per call.