updated CHANGELOG.md [ci skip]

Author: release-please[bot]

CHANGELOG.md

@@ -4,6 +4,15 @@
 
 [1]: https://pypi.org/project/google-api-core/#history
 
+## [1.18.0](https://www.github.com/googleapis/python-api-core/compare/v1.17.0...v1.18.0) (2020-05-28)
+
+
+### Features
+
+* [CBT-6 helper] Exposing Retry._deadline as a property ([#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 ([#31](https://www.github.com/googleapis/python-api-core/issues/31)) ([e4eaec0](https://www.github.com/googleapis/python-api-core/commit/e4eaec0ff255114138d3715280f86d34d861a6fa))
+* First batch of AIO integration ([#26](https://www.github.com/googleapis/python-api-core/issues/26)) ([a82f289](https://www.github.com/googleapis/python-api-core/commit/a82f2892b8f219b82e120e6ed9f4070869c28be7))
+
 ## [1.17.0](https://www.github.com/googleapis/python-api-core/compare/v1.16.0...v1.17.0) (2020-04-14)