fix: remove extra tab binding

[PiasekDev]

Currently the logic for setting the fifc_keybinding always binds the Tab alongside what the user has configured. This does not seem necessary, since the code above the bind takes care of setting fifc_keybinding to a default value, so a single bind should be enough and allow for a user override.

fifc/conf.d/fifc.fish

Lines 6 to 17 in a01650c

	if status is-interactive
	# Keybindings
	set -qU fifc_keybinding
	or set -U fifc_keybinding \t
	set -qU fifc_open_keybinding
	or set -U fifc_open_keybinding ctrl-o
	for mode in default insert
	bind --mode $mode \t _fifc
	bind --mode $mode $fifc_keybinding _fifc
	end

Looking at the code this seems to be a regression from 64433fa. It looks like this worked previously.
Unless there is a reason for keeping it this way, this PR should restore the functionality, by removing the extraneous bind.