fix: use semver-coerced versioning

I've noticed that truncated versioning upgrades is no longer working.

Looking at the logs in Renovate, the versions are reporting as invalid:

 {
  "depName": "goreleaser/goreleaser",
  "currentValue": "2.3",
  "datasource": "github-releases",
  "versioning": "semver",
  "replaceString": " 2.3 # datasource=github-releases depName=goreleaser/goreleaser
",
  "updates": [],
  "packageName": "goreleaser/goreleaser",
  "warnings": [],
  "skipReason": "invalid-value"
}

This is an attempt to fix this situation by switching to coerced semver, which allows coersion of truncated version numbers.

cc @reprazent for visibility.