Update Security String to 2021-08-01 am: 719f8e6ff2 am: 731c612c5a am: 2b5cc45a3b

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/14967096

Change-Id: I83c72777cf01ff01eb99c08f48efa1522fb147e5
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 037b0aa..16de5ae 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 := 2021-07-01
+      PLATFORM_SECURITY_PATCH := 2021-08-01
 endif
 .KATI_READONLY := PLATFORM_SECURITY_PATCH