mrregister: Fix formatting

Resolves changes proposed in e073be5 (#2700) against introduction of clang-format (#2652).

cmd/mrregister.cpp

@@ -478,7 +478,7 @@ void run() {
     case 3:
       rigid_estimator = Registration::None;
     default:
-      assert (false);
+      assert(false);
     }
   }