Apologies, I missed that you were updating a package from 0.6.4 to 0.7 - I believe you could have generated the necessary Manifest.toml and Project.toml using (Modia) pkg> develop . when navigated to the location of your package and activating its environment. If a REQUIRE exists, the new Pkg seems (from my observations) to take the REQUIRE file and generate both Manifest and Project.toml from it.
There may be some inconsistencies though, as mentioned here.