refactor: module -> module_ with typedef (#2544)

* WIP: module -> module_ without typedef

* refactor: allow py::module to work again
diff --git a/tests/test_class.cpp b/tests/test_class.cpp
index 3ca9d2a..2d4aef7 100644
--- a/tests/test_class.cpp
+++ b/tests/test_class.cpp
@@ -172,12 +172,12 @@
     struct MismatchDerived2 : MismatchBase2 { };
 
     m.def("mismatched_holder_1", []() {
-        auto mod = py::module::import("__main__");
+        auto mod = py::module_::import("__main__");
         py::class_<MismatchBase1, std::shared_ptr<MismatchBase1>>(mod, "MismatchBase1");
         py::class_<MismatchDerived1, MismatchBase1>(mod, "MismatchDerived1");
     });
     m.def("mismatched_holder_2", []() {
-        auto mod = py::module::import("__main__");
+        auto mod = py::module_::import("__main__");
         py::class_<MismatchBase2>(mod, "MismatchBase2");
         py::class_<MismatchDerived2, std::shared_ptr<MismatchDerived2>,
                    MismatchBase2>(mod, "MismatchDerived2");