tmux window detection broken in fish 3.2

[gpanders]

fish 3.2.0 introduced the following change:

fish will now always attempt to become process group leader in interactive mode (#7060). This helps avoid hangs in certain circumstances, and allows tmux's current directory introspection to work (#5699).

This means that the check in __done_is_tmux_window_active no longer works in fish 3.2.0 or later:

if status is-login
    set tmux_fish_pid $fish_pid
else
    set tmux_fish_pid (ps -o ppid= -p $fish_pid)
end

The if check needs to be changed to check for fish versions 3.2.0 or later or status is-login.