cli: cmdoptions: Mark always_unzip as depreceated

Author: Noah Gorny

src/pip/_internal/cli/cmdoptions.py

@@ -840,6 +840,8 @@ def _handle_no_use_pep517(option, opt, value, parser):
     action='store_true',
     help=SUPPRESS_HELP,
 )  # type: Callable[..., Option]
+# This way we know we can ignore this option in various docs auto generation
+setattr(always_unzip, 'deprecated', True)
 
 
 def _handle_merge_hash(option, opt_str, value, parser):