MNT: Remove pinning to freetype 2.7
MNT: Remove pinning to freetype 2.7

Replace with using testing packages for matplotlib from conda-forge.

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