Fixed linter errors in workflow files output stages

[joniohtonen]

Fixed slew of linter erros in workflow files found by dependabot.

Closes #37

Background

Dependabot found a slew of linter warnings and false positive errors in workflow files. These stemmed from self-hosted runners' labels as well as missing quotes in workflow jobs' output stages. Encapsulation errors were not detected by vanilla shellcheck, as it handles only .sh files and can't dive into the scripting inside the workflows, meanwhile actionlint can actually run shellcheck against scripting inside the workflows and actions so it is a good idea to include it in the pre-commit as well.

Goals

Fix linter errors/warnings. Include actionlint in pre-commit hook to prevent similar issues in the future.

Tasks

• Fix some $GITHUB_OUTPUT derived linter notices
• Add yaml configuration for actionlint to disregard certain static runner labels like build-only.
• Add actionlint as one of the linters in pre-commit, with shellcheck disabled to due to missing option to disregard certain directives causing a lot of false positives.
• Disable one shellcheck directive when running actionlint in pr-check workflow

Tests

• Smoke test.

Workflow changes are cosmetic, testing not necessary.