[Fix #56 An error occurred , Fix #58 An error occurred ] Remove the SHELL argument

This fixes the tmux launch_msg() error.

plugins/tmux/init.zsh

@@ -27,7 +27,7 @@ if (( $SHLVL == 1 )) && zstyle -t ':omz:plugin:tmux:auto' start; then
   if [[ -n "$session" ]]; then
     exec tmux attach-session -t "$session"
   else
-    exec tmux new-session "$SHELL -l"
+    exec tmux new-session
   fi
 fi