Space does not toggle items in choose multi-select

Hi!

In Gum 2.0.0, Space does not toggle an item in gum choose --no-limit; x and Tab still work.

To reproduce, run:

printf '%s\n' one two | gum choose --no-limit

Press Space. The highlighted item should toggle, but nothing happens.

The choose keymap registers a literal " ", while KeyPressMsg.String() returns "space" and key.Matches compares the strings exactly. Changing the binding to "space" should fix it.

Environment: macOS, Homebrew, Gum 2.0.0.