Add Dependabot cooldown (default-days: 3)

[bushidocodes]

This repo has a .github/dependabot.yml. Add a cooldown block with default-days: 3 to each updates entry so version bumps wait a few days after release before Dependabot opens a PR (avoids getting hit by a bad/yanked release the same day it ships).

Example:

updates:
  - package-ecosystem: "npm"
    directory: "/"
    schedule:
      interval: "weekly"
    cooldown:
      default-days: 3

Add the cooldown key (indented the same as schedule) under each package-ecosystem entry in this repo's dependabot.yml.

Reference: https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file#cooldown