ci(action): update actions/add-to-project action to v0.6.0

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/add-to-project](https://togithub.com/actions/add-to-project)
| action | minor | `v0.5.0` -> `v0.6.0` |

---

### Release Notes

<details>
<summary>actions/add-to-project (actions/add-to-project)</summary>

###
[`v0.6.0`](https://togithub.com/actions/add-to-project/compare/v0.5.0...v0.6.0)

[Compare
Source](https://togithub.com/actions/add-to-project/compare/v0.5.0...v0.6.0)

</details>

---

### Configuration

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are satisfied.

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rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update
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---

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.github/workflows/add_to_octokit_project.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     continue-on-error: true
     steps:
-      - uses: actions/add-to-project@v0.5.0
+      - uses: actions/add-to-project@v0.6.0
         with:
           project-url: https://github.com/orgs/octokit/projects/10
           github-token: ${{ secrets.OCTOKITBOT_PROJECT_ACTION_TOKEN }}