Upgrade to node v18

[melange396]

The update to COVIDcast v3.2.10 in https://github.com/cmu-delphi/www-main/pull/957 broke the build when i merged it in... I think this is because it introduced some dependencies that require node version 18+ (search https://github.com/cmu-delphi/www-main/blob/9bf7a77e17121279727046fb442e66891d6f25d8/package-lock.json for node": ">=18 to find them). Hopefully this appeases the build process....

[netlify[bot]]

✅ Deploy Preview for cmu-delphi-main ready!

Name	Link
🔨 Latest commit	e0e56ab37b1798cb0af1bd86d5a6a125d6b2d19d
🔍 Latest deploy log	https://app.netlify.com/sites/cmu-delphi-main/deploys/662815890993c200081eb9eb
😎 Deploy Preview	https://deploy-preview-959--cmu-delphi-main.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[melange396]

This was still broken after my initial commit -- it looks like the fatal error was actually:

npm ERR! `npm ci` can only install packages when your package.json and package-lock.json or npm-shrinkwrap.json are in sync. Please update your lock file with `npm install` before continuing.
npm ERR! 
npm ERR! Invalid: lock file's katex@0.16.9 does not satisfy katex@0.16.10

and dependabot fixed this file sync problem as part of https://github.com/cmu-delphi/www-main/pull/960 , which i just merged into here and got a successful build. This PR should still fix the WARNINGS that i saw, which were numerous but looked like:

npm WARN EBADENGINE Unsupported engine {
npm WARN EBADENGINE   package: 'cli-truncate@4.0.0',
npm WARN EBADENGINE   required: { node: '>=18' },
npm WARN EBADENGINE   current: { node: 'v1[6](https://github.com/cmu-delphi/www-main/actions/runs/8806124386/job/24170226118#step:5:7).20.2', npm: '8.19.4' }
npm WARN EBADENGINE }
npm WARN EBADENGINE Unsupported engine {
npm WARN EBADENGINE   package: 'string-width@[7](https://github.com/cmu-delphi/www-main/actions/runs/8806124386/job/24170226118#step:5:8).1.0',
npm WARN EBADENGINE   required: { node: '>=18' },
npm WARN EBADENGINE   current: { node: 'v16.20.2', npm: '[8](https://github.com/cmu-delphi/www-main/actions/runs/8806124386/job/24170226118#step:5:9).19.4' }
npm WARN EBADENGINE }
...

[melange396]

this last commit updates node in the netlify environment, to match what github is now using in its actions: and it also updates the npm version to match github actions, as well as the hugo version to match #944