bpo-40268: Remove unused pycore_pymem.h includes (GH-19531)

diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 30bc739..06ead2b 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -3,10 +3,10 @@
 #define PY_SSIZE_T_CLEAN
 
 #include "Python.h"
-#include "pycore_abstract.h"   // _PyIndex_Check()
+#include "pycore_abstract.h"      // _PyIndex_Check()
 #include "pycore_bytes_methods.h"
 #include "pycore_object.h"
-#include "pycore_pymem.h"
+#include "pycore_pymem.h"         // PYMEM_CLEANBYTE
 
 #include "pystrhex.h"
 #include <stddef.h>