bpo-31279: Silence -Wstringop-overflow warning. (#3207)

diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 22dd810..857a1aa 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -224,7 +224,7 @@
             return -1;
         }
         memcpy(sval, PyByteArray_AS_STRING(self),
-               Py_MIN(requested_size, Py_SIZE(self)));
+               Py_MIN((size_t)requested_size, (size_t)Py_SIZE(self)));
         PyObject_Free(obj->ob_bytes);
     }
     else {