PMGR-10732 Bumps node version to 16

[jeffreyazevedo]

Our fork has diverged a bit from sfdx-actions, however before trying to merge those few changes into our fork I tried changing just the node version and nothing else to see if that was sufficient, and it appears to work fine in my test builds. Do we care about bringing in any other changes besides that? None of them seem particularly functional but rather just just file path changes, and apparently they aren't necessary changes for the thing to work?

master...sfdx-actions:setup-sfdx:master

[daveespo]

It's worse than that -- they never merged the PR for the tarball-url override which lets us build the nightlies against the RC CLI

sfdx-actions#9

There is a different syntax I just learned about "two dot diff" vs "three dot diff" -- this is the diff between the two repos:

https://github.com/patronmanager/setup-sfdx/compare/master..sfdx-actions:setup-sfdx:master

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/about-comparing-branches-in-pull-requests#three-dot-and-two-dot-git-diff-comparisons

I think we're likely to be forever diverged from the main setup-sfdx repo and that's fine ..