Update Security String to 2021-01-01 am: 6441bc7ca3 am: cc0c1b00b6

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

Change-Id: Iab2faef2dcaaba49ff479003b35d5d9ff703c9b1
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 0bf450b..eddc755 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -181,7 +181,7 @@
     #  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