Name of mpy-cross executable for macos changing

[jepler]

In CircuitPython we plan to update the version of macos used to build mpy-cross, as macos 11 runners are deprecated and due for removal. At the same time, we renamed the binary, removing the macos version number specifier: https://github.com/adafruit/circuitpython/pull/9329

This change will probably first roll out in circuitpython 9.0.6 and circuitpython 9.1.0-beta.3.

Based on code search, this change will likely affect this project.