Add GitHub Actions workflow JSON schema validation task/CI

[umbynos]

There is a community created JSON schema for GitHub Actions workflows:
https://json.schemastore.org/github-workflow
Although not official, I have found this to be well done and actively maintained (the PRs I submitted are merged within a matter of hours).

I have found this to be useful and set up a "template" workflow:

https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-workflows-task.md

which means it can be added to any repository with a simple copy/paste operation.

That template is already in use in several other repos for some time.

Silvano suggested adding it also to the Arduino CLI repo, and I am in agreement that this should be considered.

Related

• Add Taskfile for common project actions arduino-lint#4
• Add CI workflow to lint configuration files arduino-lint#6

[alessio-perugini]

This might be helpful:
https://rhysd.github.io/actionlint/