DAEValidator: fix gcc-13 build

[trofi]

On gcc-13 c++ headers don't include <stdint.h> implicitly any more.
This exposed build failure as:

/build/source/DAEValidator/library/src/XmlDoc.cpp: In member function 'virtual void opencollada::XmlDoc::readFile(const std::string&)':
/build/source/DAEValidator/library/src/XmlDoc.cpp:59:17: error: 'uint32_t' was not declared in this scope
   59 |                 uint32_t signature = *reinterpret_cast<const uint32_t*>(content.data());
      |                 ^~~~~~~~

[CLAassistant]

All committers have signed the CLA.