MNT: Update NEXRAD for new message size
MNT: Update NEXRAD for new message size

With latest RDA Build 18.0, the size of the status message has increased
with some spare bytes. Just include the spares in the size check for
now.

ahaberlie/MetPy,ShawnMurd/MetPy,jrleeman/MetPy,Unidata/MetPy,ahaberlie/MetPy,dopplershift/MetPy,jrleeman/MetPy,Unidata/MetPy,dopplershift/MetPy