operationRef is a URI-reference

Restore these "format" values to the schemas, which were removed
when they were removed from the Server Object's "url" field, which
is a template and not a URI-reference.

Author: handrews

schemas/v3.0/schema.yaml

@@ -980,6 +980,7 @@ definitions:
         type: string
       operationRef:
         type: string
+        format: uri-reference
       parameters:
         type: object
         additionalProperties: {}

schemas/v3.1/schema.yaml

@@ -622,6 +622,7 @@ $defs:
     properties:
       operationRef:
         type: string
+        format: uri-reference
       operationId:
         type: string
       parameters: