Bump Security String to 2021-05-05

Implemented:
============
CVE:            References:     Type:   Severity:       Updated AOSP versions:
CVE-2021-0473   A-179687208     RCE     Critical        8.1, 9, 10, 11
CVE-2021-0474   A-177611958     RCE     Critical        8.1, 9, 10, 11
CVE-2021-0481   A-172939189     EoP     High            8.1, 9, 10, 11

Previously Implemented:
============
CVE:            References:     Type:   Severity:       Updated AOSP versions:
None

Not Implemented:
================
CVE:            References:     Type:   Severity:       Updated AOSP versions:
None

Not Applicable (platform source):
=================================
CVE:            References:     Type:   Severity:       Updated AOSP versions:
CVE-2021-0466   A-154114734     ID      High            10
CVE-2021-0472   A-176801033     EoP     High            9, 10, 11
CVE-2021-0475   A-175686168     RCE     Critical        10, 11
CVE-2021-0476   A-169252501     EoP     High            9, 10, 11
CVE-2021-0477   A-178189250     EoP     High            8.1, 9, 10, 11
CVE-2021-0480   A-174493336     ID      High            8.1, 9, 10, 11
CVE-2021-0482   A-173791720     EoP     High            11
CVE-2021-0484   A-173720767     ID      High            8.1, 9, 10, 11
CVE-2021-0485   A-174302616     EoP     High            11
CVE-2021-0487   A-174046397     EoP     High            11

Signed-off-by: L.W.Reek <syphyr@gmail.com>

Change-Id: Iba7f050223e18de2ffba09d26ca9f2b985b97514