Dependabot configuration to update actions in workflow

[ScottBrenner]

Overview

Noticed the actions used in https://github.com/fossas/fossa-cli/blob/master/.github/workflows/bench.yml are outdated, proposing a Dependabot configuration to update - automates https://github.com/fossas/fossa-cli/commit/b4b5d0b77cfcdac3fda7e53a0797adf678479e9e

Resolves warning on executions ex. https://github.com/fossas/fossa-cli/actions/runs/7820548996

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3 ...

Suggest enabling https://docs.github.com/en/code-security/dependabot/working-with-dependabot/about-dependabot-on-github-actions-runners#enabling-or-disabling-for-your-repository as well

References

https://docs.github.com/en/actions/security-guides/using-githubs-security-features-to-secure-your-use-of-github-actions#keeping-the-actions-in-your-workflows-secure-and-up-to-date,

Checklist

• [ ] I added tests for this PR's change (or explained in the PR description why tests don't make sense).
• [ ] If this PR introduced a user-visible change, I added documentation into docs/.
• [ ] If this PR added docs, I added links as appropriate to the user manual's ToC in docs/README.ms and gave consideration to how discoverable or not my documentation is.
• [ ] If this change is externally visible, I updated Changelog.md. If this PR did not mark a release, I added my changes into an # Unreleased section at the top.
• [ ] If I made changes to .fossa.yml or fossa-deps.{json.yml}, I updated docs/references/files/*.schema.json AND I have updated example files used by fossa init command. You may also need to update these if you have added/removed new dependency type (e.g. pip) or analysis target type (e.g. poetry).
• [ ] If I made changes to a subcommand's options, I updated docs/references/subcommands/<subcommand>.md.

[ScottBrenner]

Hey @csasarak mind reviewing?