v0.16.0

• Added. OpenAPI 3.1 schemas now support prefixItems, contains with
  minContains/maxContains, dependentRequired, dependentSchemas, and
  unevaluatedProperties/unevaluatedItems (#157). These keywords are
  compiled, shape-checked, eagerly parsed, and included in directional
  rewrites; contentSchema remains fail-closed.
• Added. OpenAPI 3.1 schemas support the conditional keywords if,
  then and else (#157). Each is a subschema the compiler emits, the load
  -time check walks, and the backend evaluates under draft 2020-12, at any
  depth and nested inside one another; a document using a conditional
  required — ordinary OpenAPI today — is loadable instead of
  InvalidContract. The directional rewrite reaches all three branches, so a
  readOnly/writeOnly property required inside a conditional is not required
  of the direction that does not own it, exactly as at the top level. Under
  OAS 3.0 a boolean if/then/else is still refused: that dialect
  predates boolean schemas, as it does for items and not.
• Added. OpenAPI 3.1 schemas support patternProperties and
  propertyNames (#157). Both are compiled and checked at contract load, and
  the directional rewrite recurses into them, so a map of ^x--prefixed
  headers whose members are readOnly is read in the direction the exchange
  runs in rather than in both at once.