[CI] Dependabot: add a cooldown period for new releases

[jbampton]

Enforces security best practices by requiring a minimum age for new dependency releases before they are automatically updated by Dependabot.

This practice, known as a "cooldown period," helps mitigate supply chain attacks by allowing time for frequently published malicious packages to be identified.

refs apache/cloudstack#12384

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[lprimak]

I am not sure that Maven Central is susceptible to these kinds of attacks.
Maven Central scans for malware and has stricter criteria for publishing (domain ownership verification).

What do others think?

[boris-petrov]

I agree that this is not strictly needed as in the NPM ecosystem. In addition to what @lprimak mentioned as reasons, note that most exploits are done via NPM's pre-build scripts which is not a thing in the Java world - so such supply-chain attacks are much more difficult.

That's what I believe at least. Will be interested to hear opinions of others too.