mkosi: pull in bsdutils for script, used by various integration tests

mkosi: pull in bsdutils for script, used by various integration tests

4971s TEST-74-AUX-UTILS.sh[1212]: + script -ec 'networkctl edit --runtime "$NETWORK_NAME"' /dev/null
4971s TEST-74-AUX-UTILS.sh[1269]: .//usr/lib/systemd/tests/testdata/units/TEST-74-AUX-UTILS.networkctl.sh: line 55: script: command not found

Currently works due to a transitive dependency somewhere else
that is being dropped, pull it in directly given the tool is
used by the tests

(cherry picked from commit d5eb732724b22adca886c6e10941881b42b47c65)