Fix Wikidata subclass query

[ericrwolfe]

This PR fixes a bug in the query used to create the table fh-bigquery.wikidata.subclasses_20190822. The query uses a numeric_id instead of the full Wikidata ID and correctly matches an entry with its correct parent but also any numerically-matching Wikidata property.

As a result, an query for the parent classes of an item like Q18599 short-term memory would return both its superclass Q492 memory as well as the unrelated property P492 OMIM ID:

SELECT * FROM `fh-bigquery.wikidata.subclasses_20190822` where numeric_id = 18599 and level = 1;

This PR simply excludes Wikidata properties with the filter type='item'.