lib: support alacritty $TERM in title function

lib/termsupport.zsh

@@ -17,7 +17,7 @@ function title {
   : ${2=$1}
 
   case "$TERM" in
-    cygwin|xterm*|putty*|rxvt*|konsole*|ansi|mlterm*)
+    cygwin|xterm*|putty*|rxvt*|konsole*|ansi|mlterm*|alacritty)
       print -Pn "\e]2;${2:q}\a" # set window name
       print -Pn "\e]1;${1:q}\a" # set tab name
       ;;