chore: add Dependabot config with cooldown

[skonefal]

• Adds Dependabot configuration for the repository's package ecosystems.
• Monthly update schedule with a 7-day cooldown before update PRs are opened.
• Groups updates into security, minor-and-patch, and major.

[bh2smith]

Failing test is due to expired test query executions. Will replace with a new one (in a separate PR).

[bh2smith]

This here will fix your test failures (and permanently ensure we don't have to keep updating JobIds for tests):

#41