chore: Included githubactions in the dependabot config (#19100)

This should help with keeping the GitHub actions updated on new releases. This will also help with keeping it secure.

Dependabot helps in keeping the supply chain secure https://docs.github.com/en/code-security/dependabot

GitHub actions up to date https://docs.github.com/en/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot

https://github.com/ossf/scorecard/blob/main/docs/checks.md#dependency-update-tool
Signed-off-by: naveen <[email protected]>