Bug 1721337 - run simple-fuzzing test with python3. r=decoder

python 2 is apparently no longer in the docker image since bug 1719622.

Differential Revision: https://phabricator.services.mozilla.com/D120319

taskcluster/ci/fuzzing/kind.yml

@@ -42,4 +42,4 @@ jobs:
             using: run-task
             command: >-
                 cd $MOZ_FETCHES_DIR &&
-                python tools/fuzzing/smoke/smoke.py
+                python3 tools/fuzzing/smoke/smoke.py