Update md4qt to 2.4.2 (#3080)

packages/m/md4qt/xmake.lua

@@ -7,6 +7,7 @@ package("md4qt")
     add_urls("https://github.com/igormironchik/md4qt/archive/refs/tags/$(version).tar.gz",
              "https://github.com/igormironchik/md4qt.git")
 
+    add_versions("2.4.2", "76f3228dd9afa2661fe9326b51e5ec8dc29e364f99fb0f94704792610d543fa2")
     add_versions("2.1.0", "cfbf515adecd798a3f1a4f2e007021b4b31742dd0b36805c273b3b8316fd820d")
 
     add_configs("qt6", {description = "Use Qt6", default = true, type = "boolean"})