CMake include path issue

[derpda]

Once again thank you for putting this together, and for reacting to the issues/PRs so quickly.

Issue

When using this library through

FetchContent_Declare(ByteTrackCpp
  GIT_REPOSITORY  https://github.com/Vertical-Beach/ByteTrack-cpp.git
  GIT_TAG         main
  GIT_SHALLOW     ON)
FetchContent_MakeAvailable(ByteTrackCpp)
# ...
target_link_libraries(my_lib bytetrack)

in my project, the include paths needed for the bytetrack library are not forwarded. Checking a bit further,

get_target_property(bytetrack_INCLUDE_DIRS bytetrack INTERFACE_INCLUDE_DIRECTORIES)
message(STATUS "ByteTrack include dirs: ${bytetrack_INCLUDE_DIRS}")

shows that INTERFACE_INCLUDE_DIRECTORIES are not set.

I will open another small PR fixing this once the current one is merged!