build-unit-test-docker: Update lcov
build-unit-test-docker: Update lcov

Needed to move to the gcc-9 which has a modified coverage metadata
format.

Change-Id: I6d5a2767dbb3f0a1eb081ac02c896d189f586798
Signed-off-by: William A. Kennington III <30fff5198f4d10ca1117e5f3ec82f3b4b8900d81@google.com>

openbmc/openbmc-build-scripts,openbmc/openbmc-build-scripts