gzip option of sql_to_gcs operator don't compress the data file

[nullhack]

Apache Airflow version: 1.10.9

What happened:

When using sql_to_gcs with the option gzip=True, the output data file in gcs is not compressed (and instead the schema file is compressed)

What you expected to happen:

When the option gzip=True, I would expect the data file to be compressed using gzip and no changes to the schema file

How to reproduce it:

Just use sql_to_gcs operator in any project, defining gzip=True.

Expected result:
The output data file will not be compressed but the schema file will be compressed.

[boring-cyborg]

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