Depending on the local changes, running 'make containerized-test' fails
with an error like:
level=error msg="Running error: gofmt: error computing diff: exec: \"diff\": executable file not found in $PATH"
Installing the diffutils package makes sure 'go fmt' finds the
executable.
Signed-off-by: Niels de Vos <ndevos@redhat.com>
11e1eda98b