replace :3 substrings with :2

[4gra]

I'm not sure exactly why the first three characters were being removed (perhaps the syntax changed or bash wasn't really being used despite the shebang line?) but on my Mac (running MacOS 15.x) this results in filenames being truncated (i.e. "./myApp.ipa" truncated to "yApp.ipa") so this change restores functionality.