[release-branch.go1.15] go1.15.13

Change-Id: Ib0907538e78ef9b272be8858bc8b52c8b7d6c71a
Reviewed-on: https://go-review.googlesource.com/c/go/+/324551
Run-TryBot: David Chase <drchase@google.com>
Trust: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>
diff --git a/VERSION b/VERSION
index 1a6490f..b818ff5 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-go1.15.12
\ No newline at end of file
+go1.15.13
\ No newline at end of file