chore: release bigtable 1.9.0 (#4024)

Co-authored-by: Christopher Wilcox <crwilcox@google.com>
diff --git a/bigtable/CHANGES.md b/bigtable/CHANGES.md
index dc5517d..08dc7d7 100644
--- a/bigtable/CHANGES.md
+++ b/bigtable/CHANGES.md
@@ -1,5 +1,12 @@
 # Changes
 
+## [1.9.0](https://www.github.com/googleapis/google-cloud-go/compare/bigtable/v1.8.0...bigtable/v1.9.0) (2021-04-30)
+
+
+### Features
+
+* **bigtable:** Customer Managed Encryption (CMEK) ([#3899](https://www.github.com/googleapis/google-cloud-go/issues/3899)) ([e9684ab](https://www.github.com/googleapis/google-cloud-go/commit/e9684ab1e8db6a148c72fc277f61dcfb0cd351b7))
+
 ## [1.8.0](https://www.github.com/googleapis/google-cloud-go/compare/v1.7.1...v1.8.0) (2021-02-24)