Bump Security String to 2020-04-05

Implemented:
============
CVE:            References:  Type:  Severity:  Updated AOSP versions:
CVE-2019-5018   A-140180629  EoP    High       8.0, 8.1, 9, 10
CVE-2019-8457   A-140182003  ID     High       8.0, 8.1, 9, 10
CVE-2019-9936   A-140181188  ID     Moderate   8.0, 8.1, 9, 10
CVE-2020-0070   A-148159613  RCE    Critical   8.0, 8.1, 9, 10
CVE-2020-0071   A-147310721  RCE    Critical   8.0, 8.1, 9, 10
CVE-2020-0072   A-147310271  RCE    Critical   8.0, 8.1, 9, 10
CVE-2020-0073   A-147309942  RCE    Critical   8.0, 8.1, 9, 10
CVE-2020-0081   A-144028297  EoP    High       8.0, 8.1, 9, 10

Not Implemented:
================
None

Not Applicable (platform source):
=================================
CVE:            References:  Type:  Severity:  Updated AOSP versions:
CVE-2020-0078   A-144766455  EoP    High       9, 10
CVE-2020-0079   A-144506242  EoP    High       9, 10
CVE-2020-0080   A-144092031  EoP    High       10
CVE-2020-0082   A-140417434  EoP    High       10

Change-Id: Ie92a0636e7deed5413fc968309f56bd8e31705f5