Fix RealVect crossProduct (#445)

Another fix for AMReX-Codes/amrex#4430

Author: AlexanderSinn

src/Base/RealVect.cpp

@@ -93,7 +93,7 @@ void init_RealVect(py::module &m) {
           .def(py::self * py::self)
           .def("dotProduct", &RealVect::dotProduct, "Return dot product of this vector with another")
 #if (AMREX_SPACEDIM == 3)
-          .def("crossProduct", &RealVect::crossProduct, "Return cross product of this vector with another")
+          .def("crossProduct", &RealVect::crossProduct<>, "Return cross product of this vector with another")
 #endif
           .def("__mul__",
                py::overload_cast<Real>(&RealVect::operator*, py::const_))