Update prow.sh

Co-authored-by: Patrick Ohly <patrick.ohly@intel.com>

Author: humblec

prow.sh

@@ -1257,7 +1257,7 @@ main () {
         fi
 
         if tests_need_non_alpha_cluster; then
-	    # Need to (re)create the cluster.
+            # Need to (re)create the cluster.
             start_cluster "${CSI_PROW_E2E_GATES}" || die "starting the non-alpha cluster failed"
 
             # Install necessary snapshot CRDs and snapshot controller