Committee wrongly says that `head` is not supported in OpenAPI v3

[Mihajlo Ilijić]

Running committee with a schema that has head method raises following error:

RuntimeError:
       Committee OpenAPI3 not support head method

But OpenAPI v3 spec says it's supported. I can also confirm that schema is properly rendered in ReDoc.

[Janusz Mordarski]

@ota42y any chance this can be released as 4.x before 5 milestone?