Update Security String to 2021-10-01 am: f54f3e8118 am: 102502b088 am: 5d40b4be24

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/15546870

Change-Id: I027ad5e4e12ff265d0f4602fedc9aed24ea6ab09
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 9a139da..b5c9d18 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 := 2021-09-01
+      PLATFORM_SECURITY_PATCH := 2021-10-01
 endif
 .KATI_READONLY := PLATFORM_SECURITY_PATCH