Cast of "wildcard" schemas

[zoten]

Hi everyone! Thanks as always for the work!
Poking around with complex specs, I found the use of "wildcard" shortcuts for expressing "any" schema, like in this modified example

PatchItem:
      properties:
        from:
          type: string
        op:
          $ref: '#/components/schemas/PatchOperation'
        path:
          type: string
        value: {}
      required:
        - op
        - path
      type: object

that value: {} is causing OpenApiSpex Cast to fail, since the inferred type is nil and it is explicitly set as an :invalid_schema_type in current tests.
I have put up two lines to modify this behaviour, if it is ok to accept the {} schema as "whatever"
Let me know if it is acceptable, thanks!