remove pyarrow

Author: TomAugspurger

ci/deps/travis-36-cov.yaml

@@ -20,7 +20,8 @@ dependencies:
   # https://github.com/pydata/pandas-gbq/issues/271
   - google-cloud-bigquery<=1.11
   - psycopg2
-  - pyarrow=0.9.0
+  # pyarrow segfaults on load: https://github.com/pandas-dev/pandas/issues/26716
+  # - pyarrow=0.9.0
   - pymysql
   - pytables
   - python-snappy