Update Security String to 2021-01-01 am: 6441bc7ca3

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/13074489

Change-Id: I489da5f003acbd32d027cb512c7343e83a9dc144
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 4b0e9a7..001f1eb 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -186,7 +186,7 @@
     #  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