Remove redundant setting of tempfile_suffix.

Since tempfile_suffix is set in the PromptSession constructor, it does not need to be set when calling the open_input_in_editor function.

IPython/terminal/shortcuts.py

@@ -250,7 +250,6 b' def newline_autoindent_outer(inputsplitter) -> Callable[..., None]:'
 
 
 def open_input_in_editor(event):
-    event.app.current_buffer.tempfile_suffix = ".py"
     event.app.current_buffer.open_in_editor()