all: release v0.42.0

This commit will be tagged v0.42.0.

Fixes #1504

Change-Id: I1c8f74a52494e4606484f760987b69d8bf900c77
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/42890
Reviewed-by: Tyler Bui-Palsulich <tbp@google.com>
diff --git a/CHANGES.md b/CHANGES.md
index c2f4946..bbfb807 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,26 @@
 # Changes
 
+## v0.42.0
+
+- bigtable:
+  - Add an admin method to update an instance and clusters.
+  - Fix bttest regex matching behavior for alternations (things like `|a`).
+  - Expose BlockAllFilter filter.
+- bigquery:
+  - Add Routines API support.
+- storage:
+  - Add read-only Bucket.LocationType.
+- logging:
+  - Add TraceSampled to Entry.
+  - Fix to properly extract {Trace, Span}Id from X-Cloud-Trace-Context.
+- pubsub:
+  - Add Cloud Key Management to TopicConfig.
+  - Change ExpirationPolicy to optional.Duration.
+- automl:
+  - Add apiv1beta1 client.
+- iam:
+  - Fix compilation problem with iam/credentials/apiv1.
+
 ## v0.41.0
 
 - bigtable: