replace `nansum` with `sum` to avoid MSVC problem

include/evalhyd/detail/probabilist/ranks.hpp

@@ -170,7 +170,7 @@ namespace evalhyd
                             // compute the observed relative frequency
                             // $o_j = \sum_{k \in M_j} r_k$
                             xt::view(o_j, xt::all(), xt::all(), m, e, j) =
-                                    xt::nansum(
+                                    xt::sum(
                                             xt::equal(r_k_masked_sampled, j),
                                             -1
                                     );