prow.sh: pull Go version from travis.yml
prow.sh: pull Go version from travis.yml

The travis.yml is now the only place where the Go version for the
component itself needs to be configured.

kubernetes-csi/csi-lib-utils,kubernetes-csi/csi-driver-nfs,kubernetes-csi/csi-driver-nfs,kubernetes-csi/csi-driver-nfs,kubernetes-csi/external-attacher-csi,kubernetes-csi/csi-lib-utils,kubernetes-csi/csi-lib-utils