CP: Python compatibility fix (#39286) (#41063)

CP: 957412921cda4db78e0bc426329df2168625810c

Missed in https://github.com/flutter/engine/pull/39133

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Co-authored-by: Zachary Anderson <zanderso@users.noreply.github.com>
diff --git a/tools/fuchsia/build_fuchsia_artifacts.py b/tools/fuchsia/build_fuchsia_artifacts.py
index fe5dff5..f3954b2 100755
--- a/tools/fuchsia/build_fuchsia_artifacts.py
+++ b/tools/fuchsia/build_fuchsia_artifacts.py
@@ -254,6 +254,8 @@
       tag,
   ]
   stdout = subprocess.check_output(command)
+  # TODO ricardoamador: remove this check when python 2 is deprecated.
+  stdout = stdout if isinstance(stdout, str) else stdout.decode('UTF-8')
   match = re.search(r'No matching instances\.', stdout)
   if match:
     return False