Exclude test-runner.py from the rpmbuild shebang check

Exclude test-runner.py from the rpmbuild shebang check to allow it to
run under Python 2 and 3.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #8331