New Qt project dialog doesn't require a Qt version

Steps to reproduce:

1. AS, plugin, etc.
2. File -> New Qt project
3. Set the project name and location, but no "Minimum Qt version"

Expected:

    "OK" is disabled or project is created fine with some default settings

Actual:

    "OK" is enabled, clicking on it will create a directory for the project but nothing else. The dialog is not closed. Adding a version still fails because the directory exists and QtTAS doesn't accept an existing directory for the project.