build: update license file path

Author: lc-soft

xmake.lua

@@ -46,7 +46,7 @@ xpack("app")
     set_author("[email protected]")
     set_maintainer("[email protected]")
     set_copyright("Copyright (C) 2014-present, Liu Chao <[email protected]>")
-    set_licensefile("./LICENSE.md")
+    set_licensefile("./LICENSE.txt")
     set_formats("nsis", "zip")
     set_basename("lcui-quick-start-v$(version)")
     add_installfiles("dist/(**)")