vendor/liburing/ contains the upstream version of liburing. Updating it
is normally done using git subtree.
To do an update, first fetch the remote references from the liburing repo:
git remote add liburing https://github.com/axboe/liburing.git
git fetch
Then run a subtree pull, and substitute 2.3 with the right version:
git subtree pull --prefix vendor/liburing https://github.com/axboe/liburing.git liburing-2.3 --squash
Then modify the build rules over at lib/uring/dune to pick up the
right version of the shared library that's built.