ci: Replace Dependabot with Renovatebot

[alessfg]

Proposed changes

This PR enables Renovatebot for managing dependency updates on this repo and only on this repo. When using this repo as a template, a script is run that removes the Renovatebot config and enables Dependabot. This is done to account for the fact that Dependabot works out of the box on GitHub, and Renovatebot requires some level of manual configuration to enable. By defaulting to Dependabot, we always ensure there will be some level of dependency management in place.

Checklist

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• I have read the contributing guidelines.
• I have signed the F5 Contributor License Agreement (CLA).
• If applicable, I have added tests that prove my fix is effective or that my feature works.
• If applicable, I have checked that any relevant tests pass after adding my changes.
• I have updated any relevant documentation (README.md and/or CHANGELOG.md).

[Copilot]

Pull Request Overview

This PR replaces Dependabot with Renovatebot for automated dependency management. The change switches from GitHub's native Dependabot service to Renovate, which offers more advanced configuration options and dependency update strategies.

Key Changes

• Removes existing Dependabot configuration
• Adds comprehensive Renovate configuration with GitHub Actions support
• Implements automerge policies and scheduling controls

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
.github/dependabot.yml	Removes Dependabot configuration for GitHub Actions updates
.github/renovate.json	Adds Renovate configuration with GitHub Actions grouping, automerge rules, and scheduling

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[TasoOneAsia]

LGTM but did not run the script locally (commands are simple enough to not be warranted)