Make defaultExtension optional in the transforms schema

Author: avillar

ogc/bblocks/schemas/transforms.schema.yaml

@@ -135,7 +135,6 @@ $defs:
       - type: object
         required:
           - mimeType
-          - defaultExtension
         properties:
           mimeType:
             description: A concrete media type (e.g. application/xml)