Update Security String to 2020-10-01

Bug: 163542576
resolve merge conflicts of 8ee99c4fec8a377cae13b7ef15bffe0fd121e1e3 to pi-dev

Change-Id: Ie984e76e3c9d76430f49fc6224bbfa968684dfc7
Merged-In: I4973247ab66704c16446c47c6fd830a21ea2504f
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index a3377d3..edccd62 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -231,7 +231,7 @@
     #  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 := 2019-10-01
+      PLATFORM_SECURITY_PATCH := 2020-10-01
 endif
 
 ifndef PLATFORM_SECURITY_PATCH_TIMESTAMP