Dirpath must be space separated from args

This was leading to my script executing:

```sh
"osascript" /Users/josh/code/dotfiles/bin/iterm2-new-window.scpt"/Users/josh/code/dotfiles"
```

but should have been

```sh
"osascript" /Users/josh/code/dotfiles/bin/iterm2-new-window.scpt "/Users/josh/code/dotfiles"
```