Update Node version from 12 to 16

[26damb]

Updated Node to the most stable version for our current dependencies. Does not require updates to our other dependencies or package-lock.

[26damb]

@garimame It looks like all tests including builds are successful but unit(12.x) I don't see where to update that, would you happen to know how / who could help here?

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit 2e1e79f):

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[garimame]

lgtm