Update fuchsia_test_scripts_version to the latest version (#164123)

The original roll failed for unrelated reason, and it's old, I cannot
restore it anymore.
https://github.com/flutter/flutter/pull/162766

The roll will unblock fuchsia-sdk roll as well which includes an
incompatible change.

b/399136476

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DEPS

@@ -207,7 +207,7 @@ vars = {
   # The version / instance id of the cipd:chromium/fuchsia/test-scripts which
   # will be used altogether with fuchsia-sdk to setup the build / test
   # environment.
-  'fuchsia_test_scripts_version': 'g6IlaYL1_wNmk3zNj_FUU1ymBGYcgwFxZyBIUfVd4r0C',
+  'fuchsia_test_scripts_version': 'C6yhaOWh41d1qQqUXwW381AVW0SyryrPqUdwj8z4Rw4C',
 
   # The version / instance id of the cipd:chromium/fuchsia/gn-sdk which will be
   # used altogether with fuchsia-sdk to generate gn based build rules.