Pj/update ci workflows

[philj404]

Github actions for unit tests and CI builds now showing some warnings about deprecated interfaces:

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/setup-python, actions/checkout, actions/checkout, actions/checkout, actions/checkoutNode.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/setup-python, actions/checkout, actions/checkout, actions/checkout, actions/checkout

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/

This pull request updates script versions used for:

• Ubuntu version to "latest" instead of fixed at 18.04
• actions/checkout to v3
• actions/setup-python to v4

No need to rush a release yet as the old scripts still work -- but we probably want to release the change at a convenient time.

[philj404]

FYI here are two CI Actions which show the warnings. These logfiles eventually get deleted, but until then they may be helpful:

https://github.com/philj404/arduino-timer/actions/runs/3334427081
https://github.com/philj404/arduino-timer/actions/runs/3334427079

[contrem]

merged in e201968.