Update dependency net.ltgt.gradle:gradle-nullaway-plugin to v1.6.0

[slack-oss-bot]

This PR contains the following updates:

Package	Type	Update	Change
net.ltgt.gradle:gradle-nullaway-plugin	dependencies	minor	1.3.0 -> 1.6.0

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by Renovate Bot.