build-unit-test-docker: Dependency updates

fmt: 6.1.2 -> 6.2.1
catch2: 2.11.1 -> 2.12.2

Change-Id: I06d23312333f00a84104a9a6151cda58908f244d
Signed-off-by: William A. Kennington III <wak@google.com>
1 file changed