Also disable go modules for go-licenses.

go-licenses save is still failing in CI across our repos. I missed this in
tektoncd#485

I'm still mostly just guessing at fixes because I don't have a great way to repro this locally.

tekton/images/test-runner/Dockerfile

@@ -162,7 +162,7 @@ RUN apt update && apt install -y rubygems  # for mdl
 # Extra tools through go get
 RUN GO111MODULE="on" go get github.com/google/ko/cmd/[email protected] && \
     GO111MODULE="off" go get github.com/google/licenseclassifier && \
-    GO111MODULE="on" go get github.com/google/go-licenses && \
+    GO111MODULE="off" go get github.com/google/go-licenses && \
     GO111MODULE="on" go get github.com/jstemmer/go-junit-report && \
     GO111MODULE="on" go get github.com/raviqqe/liche && \
     GO111MODULE="off" go get github.com/golang/dep/cmd/dep