bpo-39509: Update HTTP status code to follow IANA (GH-18294)

Add status codes 103 EARLY_HINTS and 425 TOO_EARLY.
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index e1aa414..95eca7e 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -1440,6 +1440,8 @@
             'INSUFFICIENT_STORAGE',
             'NOT_EXTENDED',
             'NETWORK_AUTHENTICATION_REQUIRED',
+            'EARLY_HINTS',
+            'TOO_EARLY'
         ]
         for const in expected:
             with self.subTest(constant=const):