Add Renovate for automated tool updates

[leighmcculloch]

What

Add a daily Renovate GitHub Actions workflow that updates the versions of tools in the build workflow.

Why

The build matrix pins tool versions in workflow YAML, and those tool versions quickly go out of date and updating them is today a manual annoying process. Renovate can update them. Renovate's default managers do not understand the build.yml file. A custom regex is used to find versions. The 7-day age gate avoids landing brand-new releases.

[Copilot]

Pull request overview

Adds Renovate-based automation so tool versions pinned in the build matrix (.github/workflows/build.yml) can be updated automatically, rather than by hand. A new daily workflow runs Renovate using a checked-in renovate.json5 configuration that defines two custom regex managers (cargo and Go tools) plus a 7-day age gate to avoid landing brand-new releases.

Changes:

• New renovate.json5 with config:recommended, a minimumReleaseAge: '7 days' gate, and two regex custom managers targeting cargo crates and Go tools in build.yml.
• New .github/workflows/renovate.yml running daily on a schedule plus workflow_dispatch and pull_request (dry-run on PRs), with minimal global permissions and job-scoped contents: write / pull-requests: write.
• Renovate is configured against the current repo/branch so configuration on the default branch is not required.

Reviewed changes

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

File	Description
renovate.json5	New Renovate config: recommended preset, 7-day age gate, and two custom regex managers for cargo (crate datasource) and Go (go datasource, strips leading v) entries in build.yml.
.github/workflows/renovate.yml	New workflow that runs renovatebot/github-action daily (and on workflow_dispatch / pull_request dry-run) with concurrency control, empty default permissions, and write permissions scoped to the job.

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[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 380d2006ba

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[leighmcculloch]

As codex points out this will not work.