scripts/build-unit-test-docker: Update to boost 1.76.0

This is now used in openbmc/openbmc@master, so we should be using it in
the CI too.

Change-Id: I0ba9e234c1ddbb7da9694fe3eafff462604a1f83
Signed-off-by: William A. Kennington III <wak@google.com>
1 file changed