MissingPackageManifestError: Could not find one of 'package.json' manifest files in the package

Big bug in the published platformio package (2.6.7) for megatinycore, so I got the MisingPackageManifestError when I tried using platform_packages to get 2.6.10. Any ideas on how to get the latest megatinycore in platformio?

platform_packages = framework-arduino-megaavr-megatinycore @ https://github.com/SpenceKonde/megaTinyCore/

As discussed in Upgrading individual platform packages? - #4 by plateformeyeoh.