Assure Node v18 for fetch

[a22d44g66]

dde/src/job_engine/core/dde_file.js

Line 280 in 2c78cd2

let file_info_response = await fetch(full_url) // unnecessary to specify the no-cors, but it doesnt' hurt, {mode: 'no-cors'})

The line above affects the running of the job engine. This line uses fetch, which is provided by Node v18. We could prevent the server from building/running if node isn't version 18, or we could use NVM to cause node to be version 18.