Warnings with Xcode 13

[buscarini]

[...]/SourcePackages/checkouts/SwiftCommonMark/Sources/cmark/xml.c:77:30: warning: implicit conversion loses integer precision: 'unsigned long' to 'bufsize_t' (aka 'int') [-Wshorten-64-to-32]
escape_xml(dest, source, strlen((char *)source));