chore: override internalChecksFilter to warn for GitHub Actions Renovate PRs

[kitsuyui]

Summary

Override internalChecksFilter from "strict" to "warn" for GitHub Actions packages in the local Renovate config.

Problem

The shared kitsuyui/renovate-config preset sets internalChecksFilter: "strict" for all GitHub Actions packages, which means a renovate/stability-days status check that is stuck PENDING sets mergeStateStatus: UNSTABLE on the PR indefinitely.

Renovate PR #34 has been PENDING on renovate/stability-days for 15+ days, even though the 3-day minimumReleaseAge window passed long ago and all CI checks (ubuntu/macos/windows test + spellcheck) pass. Because Renovate did not re-run to update the check, the PR has been blocked from merging.

Change

.github/renovate.json5: add "internalChecksFilter": "warn" to the existing GitHub Actions package rule.

With "warn", a stuck stability-days check remains visible as a signal but does not set mergeStateStatus: UNSTABLE. Renovate PRs for GitHub Actions can proceed to merge once CI passes, even if Renovate has not re-evaluated the stability-days check.

Trade-offs

• The 3-day quarantine signal is still produced; it is demoted from a merge-blocker to a warning.
• If Renovate is running normally, stability-days transitions to SUCCESS before CI finishes and there is no observable difference.
• The risk window where a supply-chain-compromised action could slip through is the same 3-day period; changing from strict to warn means a stuck check no longer acts as an additional backstop beyond CI.

Verification

• No local lint/format/test commands (pure config repo).
• actionlint on workflow files: no issues.
• Collateral check: clean, no violations.