[fzf-tmux] Fix version check

The output of `tmux -V` starts with "tmux ".

bin/fzf-tmux

@@ -180,7 +180,7 @@ trap 'cleanup' EXIT
 envs="export TERM=$TERM "
 if [[ "$opt" =~ "-E" ]]; then
   tmux_version=$(tmux -V)
-  if [[ $tmux_version =~ ^3\.2[a-z]?$ ]]; then
+  if [[ $tmux_version =~ ^tmux\ 3\.2[a-z]?$ ]]; then
     FZF_DEFAULT_OPTS="--margin 0,1 $FZF_DEFAULT_OPTS"
   else
     FZF_DEFAULT_OPTS="--border $FZF_DEFAULT_OPTS"