druid connector: avoid using 'dimensions' for scan queries (apache#7377)

After the following PyDruid change (contained in version 0.5.2)
the Superset Histogram charts rendered with Druid data are
broken:

druid-io/pydruid@0a59a70

Bump the pydruid requirements accordingly in setup.py

Issue: apache#7368

requirements.txt

@@ -49,7 +49,7 @@ pathlib2==2.3.0
 polyline==1.3.2
 py==1.7.0                 # via retry
 pycparser==2.19           # via cffi
-pydruid==0.5.0
+pydruid==0.5.2
 python-dateutil==2.6.1
 python-editor==1.0.3      # via alembic
 python-geohash==0.8.5

superset/connectors/druid/models.py

@@ -1115,7 +1115,8 @@ def run_query(  # noqa / druid
             columns.append('__time')
             del qry['post_aggregations']
             del qry['aggregations']
-            qry['dimensions'] = columns
+            del qry['dimensions']
+            qry['columns'] = columns
             qry['metrics'] = []
             qry['granularity'] = 'all'
             qry['limit'] = row_limit