github_packages: update mediaType.
github_packages: update mediaType.

This custom type will allow better display in GitHub Packages.

claui/brew,nandub/brew,EricFromCanada/brew,sjackman/homebrew,MikeMcQuaid/brew,MikeMcQuaid/brew,claui/brew,claui/brew,vitorgalvao/brew,JCount/brew,Homebrew/brew,vitorgalvao/brew,nandub/brew,sjackman/homebrew,vitorgalvao/brew,JCount/brew,Homebrew/brew,JCount/brew,EricFromCanada/brew,EricFromCanada/brew,nandub/brew,Homebrew/brew,sjackman/homebrew,nandub/brew,claui/brew,EricFromCanada/brew,Homebrew/brew,JCount/brew,MikeMcQuaid/brew,MikeMcQuaid/brew,sjackman/homebrew,vitorgalvao/brew