C++20 introduced the <format> library to help print values nicely. We switched to it in #368. Unfortunately, the default macOS C++ compiler does not support it. There are workarounds (installing a GCC compiler and aliasing it to replace Clang) but this can be difficult, hard to remember, and overall unportable.

@ManushPatell found a 3rd party formatting library call fmt which is compatible with GCC, Clang, and only requires C++11.

Task

1. Add fmt to all project's common.lib_deps section in their platformio.ini file.

   See https://registry.platformio.org/libraries/fmtlib/fmt

   Look at how we include Embedded Template Library in the libdeps section. The line for fmt should look something like this

2. Replace all uses of <format> in the repository with the equivalent fmt call.

3. Have someone with a Mac try to build the projects (there's no reason it shouldn't work, but let's make sure)