Update Security String to 2020-04-01
Bug:149240442
(cherry picked from commit f9edfe37149cef8ffe6b8c027f6ab563fdcbbaa6)

Change-Id: I70ca2967a445b099f2938ff2f4eb5444bd0a283d
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 1e517c5..aabc98a 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -250,7 +250,7 @@
     #  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 := 2020-03-05
+      PLATFORM_SECURITY_PATCH := 2020-04-01
 endif
 .KATI_READONLY := PLATFORM_SECURITY_PATCH