Update Security String to 2021-01-01

Bug: 173545603
Change-Id: If6e59e48439ca692650a6ad7ad23535a8576a585
Merged-In: I273073a04d6981c5a58b3aebdf13249fdb46586e
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index fc20b45..77876df 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -165,7 +165,7 @@
     #  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 := 2020-12-01
+      PLATFORM_SECURITY_PATCH := 2021-01-01
 endif
 
 ifndef PLATFORM_BASE_OS