[CMake] Fix TinyXML2 cmake module for windeppack

[olivier-roussel]

Since we add Pixi support for building Windows binary releases, the new CMake module for TinyXML2 is also looking for .dll file to correctly install it inside our binary package.
However, this was breaking classical usage with WinDepPack, as dll and lib files were stored alongside and the CMake module and not inside a bin/ directory.
Locally, the build did not fail on other dependencies of the WinDepPack on my side, but I'd like some feedback of other users to check if we need to fix other CMake modules.

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