put minitrace in the build_interface link library (#874)

fixes the cmake export set when building behavior tree on standard cmake: CMake Error: install(EXPORT "behaviortree_cppTargets" ...) includes target "behaviortree_cpp" which requires target "minitrace" that is not in any export set.

CMakeLists.txt

@@ -165,7 +165,7 @@ target_link_libraries(${BTCPP_LIBRARY}
         Threads::Threads
         ${CMAKE_DL_LIBS}
         $<BUILD_INTERFACE:foonathan::lexy>
-        minitrace
+        $<BUILD_INTERFACE:minitrace>
     PUBLIC
         ${BTCPP_EXTRA_LIBRARIES}
 )