Interpreter is missing from OS Policy creation example

[coinbag-fin]

osconfig/examples/OSPolicyAssignments/gcloud/change_group.yaml

Lines 15 to 18 in 01d06e5

	enforce:
	# Changes the group to logaccess and exits with code 100.
	script:
	chgrp logaccess /var/log/auth.log && exit 100

interpreter missing within "enforce" script.

interpreter: SHELL