CI: don't specify google-auth

Author: jreback

ci/deps/travis-36-cov.yaml

@@ -17,11 +17,10 @@ dependencies:
   - numpy=1.15.*
   - openpyxl
   - pandas-gbq
+  # https://github.com/pydata/pandas-gbq/issues/271
+  - google-cloud-bigquery<=1.11
   - psycopg2
   - pyarrow=0.9.0
-  # add pydata-google-auth until for pandas-gbq, see
-  # https://github.com/conda-forge/pandas-gbq-feedstock/issues/18
-  - pydata-google-auth
   - pymysql
   - pytables
   - python-snappy