fail build if diff exists (#251)

* fail build if diff exists

Right now the build tries to detect mismatches between what is in the change versus any changes actually occurred from a clean rebuild (e.g. missed checking in any updates to generated code). However if those are present, the build logs print that out but do not cause the build to fail.

Also bumps GOVERSION to match what is used in Dockerfile so we don't have go.mod or go.sum as a reason for above.

Signed-off-by: Bob Callaway <bob.callaway@gmail.com>