Update to actions that use recent Node.js

[tgeoghegan]

On a recent run of ci-build, GitHub Actions posted a warning:

Node.js 12 actions are deprecated. For more information see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/. Please update the following actions to use Node.js 16: actions-rs/toolchain, arduino/setup-protoc

actions-rs/toolchain#219 tracks actions-rs/toolchain adopting a newer node.

arduino/setup-protoc#45 tracks arduino/setup-protoc adopting a newer node.

I believe we're blocked here until the two issues above are resolved. This might be a problem since actions-rs/toolchain doesn't seem to be maintained.

[tgeoghegan]

#685 moves us off actions-rs/toolchain altogether.

[RainbowMango]

+1
Just echo the warning message here:

Node.js 12 actions are deprecated. For more information see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/. Please update the following actions to use Node.js 16: 

arduino/setup-protoc

[RainbowMango]

cc the maintainer for help @divergentdave

[tgeoghegan]

We're aware of the problem. We're blocked on either arduino/setup-protoc#45 being resolved or finding an alternate means of installing protoc in CI.

[divergentdave]

This was resolved in #1407, which removed our need for protoc. I spot checked each of our workflows, and we're not seeing these warnings anymore.