add 2.4.x branch to dependabot

[pminz]

No description provided.

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[ryanemerson]

These rules will result in Dependabot PRs also being created for non-security updates on the 2.4.x branch, I think we only want security uploads for go and mvn. It probably makes sense to keep the actions upto date though, WDYT @pminz @Crumby ?

FYI to disable non-security updates, the configuration is as follows:

version: 2
updates:
  # Replace "npm" with your project's package ecosystem.
  # Common options: npm, pip, gomod, maven, gradle, nuget, bundler, cargo, etc.
  - package-ecosystem: "npm"
    directory: "/" # Location of package manifests
    schedule:
      interval: "daily"
    # This is the key setting:
    # It disables pull requests for VERSION updates.
    # It does NOT affect SECURITY updates.
    open-pull-requests-limit: 0

[pminz]

I agree that it does make sense to keep gitHub actions upto date, so I think we can keep the section in to continue receiving version bumps.