Quite simply, you're not allowed that character in an XML document, no matter how you mark it up. To quote the spec:
Char ::= #x9 | #xA | #xD |
[#x20-#xD7FF] | [#xE000-#xFFFD] |
[#x10000-#x10FFFF]
Roughly translated, that means that before 0x20, you're only allowed tab (0x09), newline (0x0a) and carriage return (0x0d).
The normal way to overcome this sort of issue to use another, embedded, encoding like base64.
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