chore: release 1.25.0

[release-please]

🤖 I have created a release *beep* *boop*

1.25.0 (2020-06-06)

Features

• add BigQuery storage client support to DB API (#36) (ba9b2f8)
• bigquery: add create job method (#32) (2abdef8)
• bigquery: add support of model for extract job (#71) (4a7a514)
• add HOUR support for time partitioning interval (#91) (0dd90b9)
• add support for policy tags (#77) (38a5c01)
• make AccessEntry objects hashable (#93) (23a173b)
• bigquery: expose start index parameter for query result (#121) (be86de3)
• bigquery: unit and system test for dataframe with int column with Nan values (#39) (5fd840e)

Bug Fixes

• allow partial streaming_buffer statistics (#37) (645f0fd)
• distinguish server timeouts from transport timeouts (#43) (a17be5f)
• improve cell magic error message on missing query (#58) (6182cf4)
• bigquery: fix repr of model reference (#66) (26c6204)
• bigquery: fix start index with page size for list rows (#27) (400673b)

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This PR was generated with Release Please.

[shollyman]

Peter, did you want to release this as a group, and then bump the storage dependency + use bqstorage by default as the second release, or did you have a different release strategy in mind?

[plamut]

@shollyman This was the plan, yes.

[yoshi-automation]

Release is at https://github.com/googleapis/python-bigquery/releases/tag/v1.25.0