Remove unneeded dependency on python2-devel (#1805225)
    
    python2-devel was only needed to be able to run a trivial script from
    the telemetry toolkit (telem-volts.py), which is installed into docs/,
    isn't executable, and requires an obsolete library which isn't
    packaged with Fedora anyhow.  Don't BuildRequire python2-devel, and
    don't then change the shebang to invoke python2.
    
    Upstream bug https://github.com/wb2osz/direwolf/issues/251 filed.