Add Python 3.7 to trove classifiers.
Add Python 3.7 to trove classifiers.

jayvdb/mwparserfromhell,jayvdb/mwparserfromhell,earwig/mwparserfromhell,jayvdb/mwparserfromhell,earwig/mwparserfromhell,jayvdb/mwparserfromhell,earwig/mwparserfromhell