Exclude python scripts from RPM shebang check

The newest Fedora packaging rules print warnings for scripts using the
/usr/bin/python shebang:

• WARNING: mangling shebang in /usr/bin/arc_summary.py from #!/usr/bin/python to #!/usr/bin/python2. This will become an ERROR, fix it manually!

Fedora wants all cross compatible scripts to pick python3. Since we
don't want our users to have to pick a specific version of python, we
exclude our scripts from the RPM build check.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #7360
Closes #7399