fix: compile error regarding <memory> header

[jfrascon]

Hello, there is the issue #163 in Livox-SDK repo asking for a fix in the file 'sdk_core/src/base/thread_base.h'
You already have a pull request that solves the issue, and it is really simple, just adding the "memory" header file to the previous file.
In the repo livox_ros_driver there is the same problem. It does not compile with newer versions of gcc and clang.
Reason: Livox-SDK/Livox-SDK#163 (comment)
In this repo, the fix is just addind the "memory" header into the file https://github.com/Livox-SDK/livox_ros_driver/blob/master/livox_ros_driver/timesync/timesync.h.

Please, can you include that header in this file, so we can add the this repo as a submodule of our projects instead for convenience.

Thank you.