arghparse: fix handling with python 3.11.9

In commit [0], the private function changes the tuple size it returns.
By using `*_` in the middle, we can support both extracted versions (3
and 4) of the function.

This investigation was done by ajak, thank you.

[0] python/cpython@c02b7ae

Resolves: pkgcore/pkgcheck#676
Resolves: pkgcore/pkgdev#184
Investigated-by: John Helmert III <[email protected]>
Signed-off-by: Arthur Zamarin <[email protected]>

src/snakeoil/cli/arghparse.py

@@ -774,7 +774,7 @@ def take_action(action, argument_strings, option_string=None):
         def consume_optional(start_index):
             # get the optional identified at this index
             option_tuple = option_string_indices[start_index]
-            action, option_string, explicit_arg = option_tuple
+            action, option_string, *_, explicit_arg = option_tuple
 
             # identify additional optionals in the same arg string
             # (e.g. -xyz is the same as -x -y -z if no args are required)