Update dependency com.diffplug.spotless to v8

[solrbot]

This PR contains the following updates:

Package	Type	Update	Change
com.diffplug.spotless	plugin	major	7.2.1 -> 8.1.0

---

Configuration

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

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, 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