Replace single dot with source for fish shell

Single dot has been deprecated and can cause issues with users on newer version: https://github.com/fish-shell/fish-shell/issues/310

scripts/quitcd/quitcd.fish

@@ -4,7 +4,7 @@ function n --description 'support nnn quit and change directory'
         nnn $argv
 
         if test -e $NNN_TMPFILE
-                . $NNN_TMPFILE
+                source $NNN_TMPFILE
                 rm $NNN_TMPFILE
         end
 end