Bump Security String to 2020-12-05

Implemented:
============
CVE:            References:     Type:   Severity:       Updated AOSP versions:
CVE-2020-0294   A-154915372     EoP     High            8.0, 8.1, 9, 10
CVE-2020-0458   A-160265164     RCE     Critical        8.0, 8.1, 9, 10
CVE-2020-0463   A-169342531     ID      High            8.0, 8.1, 9, 10, 11
CVE-2020-15802  A-158854097     ID      High            8.0, 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-2020-0099   A-141745510     EoP     High            8.0, 8.1, 9, 10
CVE-2020-0440   A-162627132     EoP     High            11
CVE-2020-0459   A-159373687     ID      High            8.0, 8.1, 9, 10
CVE-2020-0460   A-163413737     ID      High            11
CVE-2020-0464   A-150371903     ID      High            10
CVE-2020-0467   A-168500792     ID      High            8.1, 9, 10, 11
CVE-2020-0468   A-158484422     ID      High            10, 11
CVE-2020-0469   A-168692734     DoS     High            11
CVE-2020-0470   A-166268541     ID      High            10, 11

Change-Id: Ie011be8b6e0183c0fec82ff07a168f3c058798b3