Bug 23812: fix parsing of runc spec version

rbm.conf

@@ -383,7 +383,7 @@ ENV:
       # We will need to update this when there is a new spec version available
       runc_spec100 => sub {
         my ($out) = capture_exec('sudo', 'runc', '--version');
-        return $out =~ m/^runc version spec: 1\.0\.0$/;
+        return $out =~ m/^spec: 1\.0\.0$/m;
       },
     },
   )