Issue #26516: Fix test_capi on AIX

Fix regex for parse a pointer address.
diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index 5761686..6c940ef 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -561,7 +561,7 @@
 class MallocTests(unittest.TestCase):
     ENV = 'debug'
     # '0x04c06e0' or '04C06E0'
-    PTR_REGEX = r'(?:0x[0-9a-f]+|[0-9A-F]+)'
+    PTR_REGEX = r'(?:0x)?[0-9a-fA-F]+'
 
     def check(self, code):
         with support.SuppressCrashReport():