REV: restore pyparsing to latest version for doc builds (#501)

Author: rrjbca

setup.cfg

@@ -39,7 +39,6 @@ docs =
     sphinx-astropy
     matplotlib
     speclite>=0.14
-    pyparsing<3.0.0
 
 [options.package_data]
 skypy = data/*,data/*/*,*/tests/data/*