Add scopes as required field of OAuth Flow Object (#2673)

This makes metaschema consistent with the 3.0.x spec.

Refs #2666

Author: char0n

schemas/v3.0/schema.yaml

@@ -1,4 +1,4 @@
-id: https://spec.openapis.org/oas/3.0/schema/2020-02-25
+id: https://spec.openapis.org/oas/3.0/schema/2021-08-12
 $schema: http://json-schema.org/draft-04/schema#
 description: Validation schema for OpenAPI Specification 3.0.X.
 type: object
@@ -892,6 +892,7 @@ definitions:
     type: object
     required:
       - tokenUrl
+      - scopes
     properties:
       tokenUrl:
         type: string
@@ -911,6 +912,7 @@ definitions:
     type: object
     required:
       - tokenUrl
+      - scopes
     properties:
       tokenUrl:
         type: string
@@ -931,6 +933,7 @@ definitions:
     required:
       - authorizationUrl
       - tokenUrl
+      - scopes
     properties:
       authorizationUrl:
         type: string