Roll Fuchsia Mac SDK from nIPtQ59jG1pxyatOq... to 21nYb648VWbpxc36t... (

#38839)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/fuchsia-mac-sdk-flutter-engine
Please CC aaclarke@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

DEPS

@@ -816,7 +816,7 @@ deps = {
      'packages': [
        {
         'package': 'fuchsia/sdk/core/mac-amd64',
-        'version': 'nIPtQ59jG1pxyatOqCU00b30VYbmXFcNNXi59CDXQS8C'
+        'version': '21nYb648VWbpxc36tDxFL6TM6NfZW2mtsnqhzhNO9C0C'
        }
      ],
      'condition': 'host_os == "mac" and not download_fuchsia_sdk',