Add dependabot configuraiton

[krassowski]

Proposing to add dependabot for keeping Electron dependencies up to date. If any package updates are too aggressive we can add more ignore rules or adjust version bumping strategy.

This does not affect the security updates.

[krassowski]

We could also add schedule.day to get the update on a specific day if there is a preference. Full list of options: https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file