Remove the trailing white space I added by error

Kernel_23/test/Kernel_23/include/CGAL/_test_cls_aff_transformation_2.h

@@ -289,7 +289,7 @@ _test_cls_aff_transformation_2(const R& )
 auto unit = [](CGAL::Vector_2<R> v) { return v / CGAL::approximate_sqrt(v*v); };
  assert( dir == dir.transform(co1) || nonexact);
  assert( (unit(dir.to_vector()) - unit(dir.transform(co1).to_vector())).squared_length() < 1e-5);
- 
+
  assert( lin == lin.transform(co1) || nonexact );
 
  // even