Pin dmutils version
Pin dmutils version

As it is no longer an editable package we need to pin the version so
that pip knows to update it.

mtekel/digitalmarketplace-api,alphagov/digitalmarketplace-api,mtekel/digitalmarketplace-api,alphagov/digitalmarketplace-api,alphagov/digitalmarketplace-api,mtekel/digitalmarketplace-api,RichardKnop/digitalmarketplace-api,mtekel/digitalmarketplace-api,RichardKnop/digitalmarketplace-api,RichardKnop/digitalmarketplace-api,RichardKnop/digitalmarketplace-api