Add automatic release workflows

[fendor]

No description provided.

[sheaf]

Really good to automate the release process so that we don't have to remember how to cut a release each time. Thank you!
I'll have to trust you that it works as expected, as I've never made a release.

There is this warning in CI:

Warning: Node.js 20 actions are deprecated. The following actions are running on Node.js 20 and may not work as expected: actions/checkout@v2, actions/setup-node@v1. Actions will be forced to run with Node.js 24 by default starting June 16th, 2026. Node.js 20 will be removed from the runner on September 16th, 2026. Please check if updated versions of these actions are available that support Node.js 24. To opt into Node.js 24 now, set the FORCE_JAVASCRIPT_ACTIONS_TO_NODE24=true environment variable on the runner or in your workflow file. Once Node.js 24 becomes the default, you can temporarily opt out by setting ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION=true. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

[fendor]

These warnings are unrelated to the release workflows, we are using old versions for GHA. I've bumped the versions in b4db209, so these warnings in particular should be fixed now.

[fendor]

I'll have to trust you that it works as expected, as I've never made a release.

It is basically the same as the steps in the Makefile in particular make package and make publish, but I am usually a bit distrustful of Makefile and prefer the explicit commands or an npm script 😇 My next step might be to replace the Makefile with the npm script, but Ill postpone that after the next release.