[release-branch.go1.15-security] go1.15.1

Change-Id: I4103c524ce46d50215af5097460e514609b513c6
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/835373
Reviewed-by: Filippo Valsorda <valsorda@google.com>

VERSION

diff --git a/VERSION b/VERSION
index 4b9a234..29a7367 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-go1.15
\ No newline at end of file
+go1.15.1
\ No newline at end of file