spectral:oas ruleset doesn't recognize mutualTLS option for security scheme

[pdconant]

Describe the bug
When validating an OpenAPI spec that uses Mutual TLS, spectral lint, spectral reports that mutualTLS is not a viable security scheme. Mutual TLS support was added to Open API 3.1.

To Reproduce

1. Create a .spectral.json file containing:

{
  "extends": ["spectral:oas", "spectral:asyncapi"]
}

2. And an API spec that contains:

    "securitySchemes" : {
      "MutualTLS" : {
        "type" : "mutualTLS"
      }
    }

3. Run the command: spectral lint {path-to}/api.json --ruleset {path-to}/.spectral.json,
4. Observe the following output:

 2451:15    error  oas3-schema            Invalid security scheme.                                                                                  components.securitySchemes.MutualTLS
 2452:13    error  oas3-schema            "type" property must be equal to one of the allowed values: "apiKey", "http", "oauth2", "openIdConnect".  components.securitySchemes.MutualTLS.type

Expected behavior
Expected mutualTLS to be supported since it was added to OAS 3.1 here: OAI/OpenAPI-Specification#1764

[pdconant]

Oops -- My OPenAPI spec references OAS 3.0.1 instead of 3.1. Will fix and verify that it's working as expected.

[pdconant]

Confirmed - spectral is working exactly as expected.