CLN: Close CSV BytesIO buffer after upload. (#244) (#246)
CLN: Close CSV BytesIO buffer after upload. (#244) (#246)

While the buffer should eventually be destroyed/closed by the gc
(the timing of this is implementation-dependent), it is safer
practice to explicitly close immediately after upload.
googleapis/python-bigquery-pandas,pydata/pandas-gbq,pydata/pandas-gbq,googleapis/python-bigquery-pandas