Update dependency phoenix_live_dashboard to ~> 0.8.0

[renovate]

This PR contains the following updates:

Package	Update	Change
phoenix_live_dashboard	minor	~> 0.4.0 -> ~> 0.8.0

---

Configuration

📅 Schedule: Branch creation - "before 6am on Monday" in timezone Europe/Paris, 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 was generated by Mend Renovate. View the repository job log.

[renovate]

⚠ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: mix.lock

Command failed: mix deps.update phoenix_live_dashboard
warning: use Mix.Config is deprecated. Use the Config module instead
  config/config.exs:8

warning: use Mix.Config is deprecated. Use the Config module instead
  config/dev.exs:1

** (Mix) Hex dependency resolution failed