spanner: release v1.5.1

Change-Id: I933efb17f87733dc0168858d2b43db57e463d6fb
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/54990
Reviewed-by: Knut Olav Løite <koloite@gmail.com>
diff --git a/internal/version/version.go b/internal/version/version.go
index af9fc2f..a4f4049 100644
--- a/internal/version/version.go
+++ b/internal/version/version.go
@@ -26,7 +26,7 @@
 
 // Repo is the current version of the client libraries in this
 // repo. It should be a date in YYYYMMDD format.
-const Repo = "20200414"
+const Repo = "20200417"
 
 // Go returns the Go runtime version. The returned string
 // has no whitespace.
diff --git a/spanner/CHANGES.md b/spanner/CHANGES.md
index ee64c58..39e1139 100644
--- a/spanner/CHANGES.md
+++ b/spanner/CHANGES.md
@@ -1,5 +1,13 @@
 # Changes
 
+## v1.5.1
+
+* Fix incorrect decreasing metrics, numReads and numWrites.
+* Fix an issue that XXX fields/methods are internal to proto and may change
+  at any time. XXX_Merge panics in proto v1.4.0. Use proto.Merge instead of
+  XXX_Merge.
+* spannertest: handle list parameters in RPC interfacea.
+
 ## v1.5.0
 
 * Metrics