Roll Fuchsia Mac SDK from h3-8RUVrC889UXou7... to P7QA6bfO_Ij5dre7B... (flutter/engine#42867)

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 chinmaygarde@google.com,rmistry@google.com,zra@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

@@ -889,7 +889,7 @@ deps = {
      'packages': [
        {
         'package': 'fuchsia/sdk/core/mac-amd64',
-        'version': 'h3-8RUVrC889UXou7nSXKFK3chIflBeCfQ90VO0CLicC'
+        'version': 'P7QA6bfO_Ij5dre7BjchMdl7JhkRp3rus6-mD4Tya9wC'
        }
      ],
      'condition': 'host_os == "mac" and not download_fuchsia_sdk',