Update dependency versions to new LTS or latest tip

• Node 20 is very new at this point so 18 is the most stable LTS
• import-cwd is required for the watch script, not sure how it was imported before
• Typescript isn't on latest release (5.x) because of a conflict with react-scripts

Part of https://gitlab.developers.cam.ac.uk/uis/devops/laboratory-allocator/lab-allocator/-/issues/3 and https://gitlab.developers.cam.ac.uk/uis/devops/laboratory-allocator/lab-allocator/-/issues/4