chore: release spanner 1.16.0 (#3786)

* chore: release spanner 1.16.0

* fix: updated to include CMEK feature

Co-authored-by: skuruppu <skuruppu@google.com>
diff --git a/spanner/CHANGES.md b/spanner/CHANGES.md
index 0886540..941b3ef 100644
--- a/spanner/CHANGES.md
+++ b/spanner/CHANGES.md
@@ -1,5 +1,18 @@
 # Changes
 
+## [1.16.0](https://www.github.com/googleapis/google-cloud-go/compare/v1.15.0...v1.16.0) (2021-03-17)
+
+
+### Features
+
+* **spanner:** add `optimizer_statistics_package` field in `QueryOptions` ([18c88c4](https://www.github.com/googleapis/google-cloud-go/commit/18c88c437bd1741eaf5bf5911b9da6f6ea7cd75d))
+* **spanner/admin/database:** add CMEK fields to backup and database ([16597fa](https://github.com/googleapis/google-cloud-go/commit/16597fa1ce549053c7183e8456e23f554a5501de))
+
+
+### Bug Fixes
+
+* **spanner/spansql:** fix parsing of NOT IN operator ([#3724](https://www.github.com/googleapis/google-cloud-go/issues/3724)) ([7636478](https://www.github.com/googleapis/google-cloud-go/commit/76364784d82073b80929ae60fd42da34c8050820))
+
 ## [1.15.0](https://www.github.com/googleapis/google-cloud-go/compare/v1.14.1...v1.15.0) (2021-02-24)