Fix rate limiting in CI

[emmatown]

I think this should fix the rate limiting we're seeing because if you look at the logs, it always fails in actions/setup-node right after it logs Attempt to resolve LTS alias from manifest...(https://github.com/actions/setup-node/blob/c2dfe2df9884bf1033e0ee352d86309105ea6cf0/src/installer.ts#L44) that leads to https://github.com/actions/toolkit/blob/500d0b42fee2552ae9eeb5933091fe2fbf14e72d/packages/tool-cache/src/tool-cache.ts#L589 which does a GitHub API call so getting a rate limit error from GitHub makes sense.

So I think we can fix it by writing a version rather than use lts/*, from a cursory reading of the code in actions/setup-node doesn't try to do a call to GitHub's API when using a version range like 16. Updating our CI every time there is a new active Node LTS seems fine.

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[dcousens]

What a pain, but I understand