update to Zig 2024.1.0-mach (fix dir iter)

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

build.zig

@@ -1618,7 +1618,7 @@ fn scanSources(
  excluding_contains: []const []const u8,
 ) !void {
  const abs_dir = try std.fs.path.join(b.allocator, &.{ sdkPath("/"), rel_dir });
- var dir = std.fs.openDirAbsolute(abs_dir, .{}) catch |err| {
+ var dir = std.fs.openDirAbsolute(abs_dir, .{ .iterate = true }) catch |err| {
  std.log.err("mach: error: failed to open: {s}", .{abs_dir});
  return err;
  };