Fix tests failing in GitHub Actions
Fix tests failing in GitHub Actions

Test `test_run_duplicate_streams_timeout` fails sometimes, and after
some investigations it is found that the process used in the test
exits before considered for a Timeout.
To fix the test, the command is now replaced with another command.

Signed-off-by: Pradyumna Krishna <46f1a0bd5592a2f9244ca321b129902a06b53e03@onpy.in>

secure-systems-lab/securesystemslib,secure-systems-lab/securesystemslib