pixie tests don't support arm64 mac (m1)

[ringabout]

ref nim-lang/Nim#23290

/Users/runner/work/Nim/Nim/lib/std/assertions.nim(122) test_paths
  /Users/runner/work/Nim/Nim/lib/std/assertions.nim(36) raiseAssert
  /Users/runner/work/Nim/Nim/lib/system/fatal.nim(53) sysFatal
  Error: unhandled exception: expected raising 'PixieError', instead nothing was raised by: 
  image.fillPath(path, paint, mat3(), NonZero) [AssertionDefect]
  Error: execution of an external program failed: '/Users/runner/work/Nim/Nim/pkgstemp/pixie/tests/test_paths'