Verifier Installation

Hi,

Just want to let you know that a comma is missing in [this line](https://github.com/dlshriver/dnnv/blob/d4f59a01810cf4dac99f8f5e5b9d7a350cbfa8d7/dnnv/_manage/linux/verifiers/nnenum.py#L111) where you specify the version of scipy. This will cause an error for the installation of the nnenum verifier. 