Move CDDL job from Node 12 to Node 16 due to deprecated features

[whimboo]

See the annotations for the CDDL job:
https://github.com/w3c/webdriver-bidi/actions/runs/5186558692?pr=442

Node.js 12 actions are deprecated. Please update the following actions to use Node.js 16: actions-rs/toolchain@v1. For more information see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.

and

The set-output command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

[thiagowfx]

This is likely blocked on actions-rs/toolchain#219 and actions-rs/toolchain#221

[thiagowfx]

One idea: actions-rs/toolchain#216 (comment)

[dtolnay]

This is likely blocked on actions-rs/toolchain#219 and actions-rs/toolchain#221

The whole actions-rs org is abandoned for years, so I would recommend not blocking yourself on it being revived.

[whimboo]

Thank you David! It's great to see that [dtolnay/rust-toolchain](https://github.com/dtolnay/rust-toolchain) exists and works fine for our purpose.