chore: Included githubactions in the dependabot config

[naveensrinivasan]

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]

[jonaski]

Qt doesn't use GitHub, this needs to be submitted to Gerrit codereview (https://codereview.qt-project.org/). For instructions see: https://wiki.qt.io/Setting_up_Gerrit and https://wiki.qt.io/Gerrit_Introduction

[cla-assistant]

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