Issue
Metagraph fails to build on MacOS with AppleClang 13 (Xcode 13) as seen in this workflow run. This workflow was run on a branch identical to master, which has a workflow run that previously passed using AppleClang 12.

One possible solution would be to use macos-11 instead of macos-latest in the workflow, and recommend compiling with homebrew's g++11 on newer versions of MacOS.