Fix pack_command type annotation to accept variable-length tuples (#55)

* Initial plan

* Fix pack_command type annotation to accept variable-length tuples

Co-authored-by: mkmkme <4062234+mkmkme@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: mkmkme <4062234+mkmkme@users.noreply.github.com>

Author: Copilot

libvalkey/libvalkey.pyi

@@ -26,4 +26,4 @@ class Reader:
         self, encoding: Optional[str] = ..., errors: Optional[str] = ...
     ) -> None: ...
 
-def pack_command(cmd: Tuple[str | int | float | bytes | memoryview]): ...
+def pack_command(cmd: Tuple[str | int | float | bytes | memoryview, ...]) -> bytes: ...