chore: release 1.21.0 (googleapis#54)

* updated CHANGELOG.md [ci skip]

* updated setup.cfg [ci skip]

* updated setup.py

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>

chore: release 1.20.1 (googleapis#51)

🤖 I have created a release \*beep\* \*boop\* 
---
### [1.20.1](https://www.github.com/googleapis/python-api-core/compare/v1.20.0...v1.20.1) (2020-06-16)


### Bug Fixes

* **dependencies:** increase protobuf version ([googleapis#49](https://www.github.com/googleapis/python-api-core/issues/49)) ([1ba6095](https://www.github.com/googleapis/python-api-core/commit/1ba609592968c9d828449b89a3ade3bcaf5edd7f)), closes [googleapis#48](https://www.github.com/googleapis/python-api-core/issues/48)
---


This PR was generated with [Release Please](https://github.com/googleapis/release-please).

chore: release 1.20.0 (googleapis#45)

* updated CHANGELOG.md [ci skip]

* updated setup.cfg [ci skip]

* updated setup.py

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>

chore: release 1.19.1 (googleapis#42)

* updated CHANGELOG.md [ci skip]

* updated setup.cfg [ci skip]

* updated setup.py

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>

chore: release 1.19.0 (googleapis#39)

* updated CHANGELOG.md [ci skip]

* updated setup.cfg [ci skip]

* updated setup.py

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>

chore: release 1.18.0 (googleapis#33)

🤖 I have created a release \*beep\* \*boop\* 
---
## [1.18.0](https://www.github.com/googleapis/python-api-core/compare/v1.17.0...v1.18.0) (2020-06-04)


### Features

* [CBT-6 helper] Exposing Retry._deadline as a property ([googleapis#20](https://www.github.com/googleapis/python-api-core/issues/20)) ([7be1e59](https://www.github.com/googleapis/python-api-core/commit/7be1e59e9d75c112f346d2b76dce3dd60e3584a1))
* add client_encryped_cert_source to ClientOptions ([googleapis#31](https://www.github.com/googleapis/python-api-core/issues/31)) ([e4eaec0](https://www.github.com/googleapis/python-api-core/commit/e4eaec0ff255114138d3715280f86d34d861a6fa))
* AsyncIO Integration [Part 2] ([googleapis#28](https://www.github.com/googleapis/python-api-core/issues/28)) ([dd9b2f3](https://www.github.com/googleapis/python-api-core/commit/dd9b2f38a70e85952cc05552ec8070cdf29ddbb4)), closes [googleapis#23](https://www.github.com/googleapis/python-api-core/issues/23)
* First batch of AIO integration ([googleapis#26](https://www.github.com/googleapis/python-api-core/issues/26)) ([a82f289](https://www.github.com/googleapis/python-api-core/commit/a82f2892b8f219b82e120e6ed9f4070869c28be7))
* third batch of AsyncIO integration ([googleapis#29](https://www.github.com/googleapis/python-api-core/issues/29)) ([7d8d580](https://www.github.com/googleapis/python-api-core/commit/7d8d58075a92e93662747d36a2d55b5e9f0943e1))
---


This PR was generated with [Release Please](https://github.com/googleapis/release-please).

chore: release 1.17.0 (googleapis#7)

* updated CHANGELOG.md [ci skip]

* updated setup.cfg [ci skip]

* updated setup.py [ci skip]

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>

chore(api_core): release 1.16.0 (#10109)

chore(api_core): release 1.15.0 (#9984)

chore(api_core): release 1.14.3 (#9417)