add missing header

[OldManYellsAtCloud]

When compiling with gcc15, compiliation fails with the following error:

| In file included from ../sources/libcamera-apps-1.9.0/post_processing_stages/segmentation_tf_stage.cpp:8: | ../sources/libcamera-apps-1.9.0/post_processing_stages/segmentation.hpp:15:82: error: 'uint8_t' was not declared in this scope
|    15 |         Segmentation(int w, int h, std::vector<std::string> l, const std::vector<uint8_t> &s)

To avoid it, add the cstdint header to the offending file.

[naushir]

Change looks fine, but would you be able to reword the commit message to fit with our guidelines? A git log should show you what is needed.

[OldManYellsAtCloud]

👍
Does this version look better?

[naushir]

Thank you - that looks good!