TST: add downstream deps in 3.6 build (pandas-dev#18333)

(cherry picked from commit a39f967)

Author: jreback

ci/requirements-3.6.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+source activate pandas
+
+echo "[install 3.6 downstream deps]"
+
+conda install -n pandas -c conda-forge pandas-gbq pandas-datareader xarray geopandas seaborn statsmodels scikit-learn dask

ci/script_multi.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -e
 
 echo "[script multi]"