fixup! fixup! kresctl: cache command: output formats for 'clear' operation

Author: alesmrazek

manager/knot_resolver_manager/cli/cmd/cache.py

@@ -78,13 +78,15 @@ def register_args_subparser(
             const=DataFormat.JSON,
             action="store_const",
             dest="out_format",
+            default=DataFormat.YAML,
         )
         out_format.add_argument(
             "--yaml",
             help="Set configuration data in YAML format.",
             const=DataFormat.YAML,
             action="store_const",
             dest="out_format",
+            default=DataFormat.YAML,
         )
 
         return cache_parser, CacheCommand