Add the Metadata class to the C extension module under the correct name

Author: oschwald

HISTORY.rst

@@ -8,6 +8,9 @@ History
 
 * The C extension now correctly supports objects that implement the
   ``os.PathLike`` interface.
+* The ``Metadata`` class object is now available from the C extension
+  module as ``maxminddb.extension.Metadata`` rather than
+  ``maxminddb.extension.extension``.
 
 2.0.3 (2020-10-16)
 ++++++++++++++++++

extension/maxminddb.c

@@ -738,7 +738,7 @@ PyMODINIT_FUNC PyInit_extension(void) {
     if (PyType_Ready(&Metadata_Type)) {
         return NULL;
     }
-    PyModule_AddObject(m, "extension", (PyObject *)&Metadata_Type);
+    PyModule_AddObject(m, "Metadata", (PyObject *)&Metadata_Type);
 
     PyObject *error_mod = PyImport_ImportModule("maxminddb.errors");
     if (error_mod == NULL) {