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 <[email protected]>

Author: PradyumnaKrishna

tests/test_process.py

@@ -118,8 +118,8 @@ def test_run_cmd_arg_return_code(self):
   def test_run_duplicate_streams_timeout(self):
     """Test raise TimeoutExpired. """
     with self.assertRaises(securesystemslib.process.subprocess.TimeoutExpired):
-      securesystemslib.process.run_duplicate_streams(sys.executable + " --version",
-          timeout=-1)
+      securesystemslib.process.run_duplicate_streams(sys.executable +
+        " -c \"while True: pass\"", timeout=-1)
 
 
   def test__default_timeout(self):