fix manifest so Tox will run

Author: woodthom2

MANIFEST.in

@@ -7,6 +7,7 @@ include *.ipynb
 include *.png
 include cross_check_against_common_english_vocab.py
 include find_short_drug_names.py
+include update_version.py
 recursive-include harvesting_data_from_source *.py
 recursive-include harvesting_data_from_source *.csv
 recursive-include src *.bz2