Add dependabot label and reviewer, and track actions

[matttrach]

This will add the k3s-io/k3s-dev group to dependabot PRs.
This will add the kind/dependabot label to dependabot PRs.

This will have dependabot manage the dependencies for github actions.

This contributes to k3s-io/k3s#7398
This contributes to k3s-io/k3s#7350

I tested this by running the dependabot cli locally:

Test Scenario

{
  "input": {
    "job": {
      "package-manager": "docker",
      "allowed-updates": [
        {
          "update-type": "all"
        }
      ],
      "source": {
        "provider": "github",
        "repo": "matttrach/k3s-upgrade",
        "directory": "/",
        "commit": "7b0e5e2b68ad19db8c73ca4b2e010f99e5cd3f9b"
      },
      "credentials-metadata": [
        {
          "host": "github.com",
          "type": "git_source"
        }
      ]
    },
    "credentials": [
      {
        "host": "github.com",
        "password": "$LOCAL_GITHUB_ACCESS_TOKEN",
        "type": "git_source",
        "username": "x-access-token"
      }
    ]
  },
  "output": [
    {
      "type": "update_dependency_list",
      "expect": {
        "data": {
          "dependencies": [
            {
              "name": "alpine",
              "requirements": [
                {
                  "file": "Dockerfile.manifest",
                  "groups": [],
                  "requirement": null,
                  "source": {
                    "tag": "3.17.3"
                  }
                }
              ],
              "version": "3.17.3"
            }
          ],
          "dependency_files": [
            "/Dockerfile",
            "/Dockerfile.manifest"
          ]
        }
      }
    },
    {
      "type": "mark_as_processed",
      "expect": {
        "data": {
          "base-commit-sha": "7b0e5e2b68ad19db8c73ca4b2e010f99e5cd3f9b"
        }
      }
    }
  ]
}