chore(renovate): add config for Makefile toolchain

[weisdd]

• renovate:
  • added a custom regex manager to handle deps in Makefile / Toolchain.mk;
  • enabled updates for:
    • chainsaw;
    • controller-runtime;
    • controller-tools;
    • crdoc;
    • envtest & setup-envtest;
    • golangci-lint;
    • helm-docs;
    • kind;
    • ko;
    • kustomize;
    • yq.

NOTE: Those instructions require a GitHub token to be present, which is, presumably, the case in our setup (I have no visibility over enterprise settings). For local tests, I used: docker run --rm -v "${PWD}:/repo" -w /repo -e LOG_LEVEL=debug -e RENOVATE_GITHUB_COM_TOKEN=REDACTED renovate/renovate --platform=local --repository-cache=reset --enabled-managers regex (+ had to disable extends section inside renovate.json).

[Baarsgaard]

Nice!

I do however worry about the amount of PRs we'll be getting 😅

[weisdd]

We can always disable upgrades for some of the deps if it goes out hand. Let's see :)