bindings: Fix Python serial program init when ADIOS2 has MPI enabled

The one-argument `adios2.ADIOS(...)` constructor has two overloads
when MPI is enabled: `ADIOS(bool)` and `ADIOS(MPI4PY_Comm)`.  The
representation of `MPI4PY_Comm` is just an integer, so a call with
a `bool` may try to convert it (and fail).  Re-order the pybind11
definitions of these signatures so that the `ADIOS(bool)` is tried
first.  That way a call with a `bool` will use it and a call with
a `MPI4PY_Comm` will not convert and fall back to the proper variant.

Fixes: #2233

bindings/Python/py11glue.cpp

@@ -229,6 +229,15 @@ PYBIND11_MODULE(ADIOS2_PYTHON_MODULE_NAME, m)
                  const bool opBool = adios ? true : false;
                  return opBool;
              })
+        .def(pybind11::init<const bool>(),
+             "adios2 module starting point "
+             "non-MPI, constructs an ADIOS class "
+             "object",
+             pybind11::arg("debugMode") = true)
+        .def(pybind11::init<const std::string &, const bool>(),
+             "adios2 module starting point non-MPI, constructs an ADIOS class "
+             "object",
+             pybind11::arg("configFile"), pybind11::arg("debugMode") = true)
 #if ADIOS2_USE_MPI
         .def(pybind11::init<const adios2::py11::MPI4PY_Comm, const bool>(),
              "adios2 module starting point, constructs an ADIOS class object",
@@ -239,15 +248,6 @@ PYBIND11_MODULE(ADIOS2_PYTHON_MODULE_NAME, m)
              pybind11::arg("configFile"), pybind11::arg("comm"),
              pybind11::arg("debugMode") = true)
 #endif
-        .def(pybind11::init<const bool>(),
-             "adios2 module starting point "
-             "non-MPI, constructs an ADIOS class "
-             "object",
-             pybind11::arg("debugMode") = true)
-        .def(pybind11::init<const std::string &, const bool>(),
-             "adios2 module starting point non-MPI, constructs an ADIOS class "
-             "object",
-             pybind11::arg("configFile"), pybind11::arg("debugMode") = true)
         .def("DeclareIO", &adios2::py11::ADIOS::DeclareIO,
              "spawn IO object component returning a IO object with a unique "
              "name, throws an exception if IO with the same name is declared "