bpo-36389: Change PyMem_SetupDebugHooks() constants (GH-12782)

Modify CLEANBYTE, DEADDYTE and FORBIDDENBYTE constants: use 0xCD,
0xDD and 0xFD, rather than 0xCB, 0xBB and 0xFB, to use the same byte
patterns than Windows CRT debug malloc() and free().
diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index 3cd39d4..33c98ac 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -480,11 +480,11 @@
                  r"    The [0-9] pad bytes at p-[0-9] are FORBIDDENBYTE, as expected.\n"
                  r"    The [0-9] pad bytes at tail={ptr} are not all FORBIDDENBYTE \(0x[0-9a-f]{{2}}\):\n"
                  r"        at tail\+0: 0x78 \*\*\* OUCH\n"
-                 r"        at tail\+1: 0xfb\n"
-                 r"        at tail\+2: 0xfb\n"
+                 r"        at tail\+1: 0xfd\n"
+                 r"        at tail\+2: 0xfd\n"
                  r"        .*\n"
                  r"    The block was made by call #[0-9]+ to debug malloc/realloc.\n"
-                 r"    Data at p: cb cb cb .*\n"
+                 r"    Data at p: cd cd cd .*\n"
                  r"\n"
                  r"Enable tracemalloc to get the memory block allocation traceback\n"
                  r"\n"
@@ -500,7 +500,7 @@
                  r"    The [0-9] pad bytes at p-[0-9] are FORBIDDENBYTE, as expected.\n"
                  r"    The [0-9] pad bytes at tail={ptr} are FORBIDDENBYTE, as expected.\n"
                  r"    The block was made by call #[0-9]+ to debug malloc/realloc.\n"
-                 r"    Data at p: cb cb cb .*\n"
+                 r"    Data at p: cd cd cd .*\n"
                  r"\n"
                  r"Enable tracemalloc to get the memory block allocation traceback\n"
                  r"\n"