Update Security String to 2021-01-05

Bug: 173545603
Change-Id: I273073a04d6981c5a58b3aebdf13249fdb46586e
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 30b7da6..6ac90d8 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -240,7 +240,7 @@
     #  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 := 2020-12-05
+      PLATFORM_SECURITY_PATCH := 2021-01-05
 endif
 .KATI_READONLY := PLATFORM_SECURITY_PATCH