bpo-37648: Fixed minor inconsistency in some __contains__. (GH-14904)

The collection's item is now always at the left and
the needle is on the right of ==.
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index b6205d9..f168ad5 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -4392,7 +4392,7 @@
         return 0;
     }
     Py_INCREF(found);
-    result = PyObject_RichCompareBool(value, found, Py_EQ);
+    result = PyObject_RichCompareBool(found, value, Py_EQ);
     Py_DECREF(found);
     return result;
 }