Update Security String to 2021-05-05

resolve merge conflicts of 321db2f846e2f1d0f6a25cd0e16deb59dadf774d to rvc-qpr-dev

Bug: 182937985
Change-Id: I248e89c967a3b02e072f477594a86b568d0f94a2
(cherry picked from commit 10e01bc86527689e4bc69ef7fb0d0077cf2844bf)
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index e83b8b0..b32474d 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 := 2021-04-05
+      PLATFORM_SECURITY_PATCH := 2021-05-05
 endif
 .KATI_READONLY := PLATFORM_SECURITY_PATCH