Update ghcr.io/robert-koch-institut/mex-backend Docker tag to v0.21.0 (…

…#181)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
|
[ghcr.io/robert-koch-institut/mex-backend](https://redirect.github.com/robert-koch-institut/mex-backend)
| service | minor | `0.20.0` -> `0.21.0` |

---

### Release Notes

<details>
<summary>robert-koch-institut/mex-backend
(ghcr.io/robert-koch-institut/mex-backend)</summary>

###
[`v0.21.0`](https://redirect.github.com/robert-koch-institut/mex-backend/blob/HEAD/CHANGELOG.md#0210---2024-10-31)

[Compare
Source](https://redirect.github.com/robert-koch-institut/mex-backend/compare/0.20.0...0.21.0)

##### Changes

-   upgrade mex-common and mex-model dependencies to metadata model v3
-   apply additional linters in prep for `all` ruff linters

</details>

---

### Configuration

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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
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---

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---

This PR has been generated by [Renovate
Bot](https://redirect.github.com/renovatebot/renovate).

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.github/workflows/testing.yml

@@ -33,7 +33,7 @@ jobs:
         ports:
           - 7687:7687
       backend:
-        image: ghcr.io/robert-koch-institut/mex-backend:0.20.0
+        image: ghcr.io/robert-koch-institut/mex-backend:0.21.0
         env:
           MEX_BACKEND_API_USER_DATABASE: ${{ secrets.MEX_BACKEND_API_USER_DATABASE }}
           MEX_BACKEND_API_KEY_DATABASE: ${{ secrets.MEX_BACKEND_API_KEY_DATABASE }}

pyproject.toml

@@ -149,5 +149,5 @@ known-first-party = ["mex", "tests"]
 convention = "google"
 
 [build-system]
-requires = ["pdm-backend==2.4.2"]
+requires = ["pdm-backend==2.4.3"]
 build-backend = "pdm.backend"