Update Security String to 2021-05-01 am: 6f23fe1713 am: 74a0816d49

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/13919906

Change-Id: I940aee102ed107695cee2e3820034a2ad748ec35
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index a6347a1..3d0405a 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -250,7 +250,7 @@
     #  It must be of the form "YYYY-MM-DD" on production devices.
     #  It must match one of the Android Security Patch Level strings of the Public Security Bulletins.
     #  If there is no $PLATFORM_SECURITY_PATCH set, keep it empty.
-      PLATFORM_SECURITY_PATCH := 2021-03-01
+      PLATFORM_SECURITY_PATCH := 2021-05-01
 endif
 .KATI_READONLY := PLATFORM_SECURITY_PATCH