http/h1_reason_phrases: Add 103 now that RFC 8297 is published

Author: daurnimator

http/h1_reason_phrases.lua

@@ -5,6 +5,7 @@ local reason_phrases = setmetatable({
 	["100"] = "Continue";
 	["101"] = "Switching Protocols";
 	["102"] = "Processing";
+	["103"] = "Early Hints";
 
 	["200"] = "OK";
 	["201"] = "Created";