Fix Clang compatibility

[mtxn2147]

fix compatibility issue with platforms using clang. Due to the difference in standard implementations, a change of the C++ standard from 14 to 17 is required to properly build the project on these platforms.

compilation errors with clang18:

...
/usr/include/unicode/localpointer.h:561:26: error: 'auto' not allowed in template parameter until C++17
...
/usr/include/unicode/uenum.h:69:69: error: value of type 'void (UEnumeration *)' is not implicitly convertible to 'int'
...

[mtxn2147]

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