chore(deps): update gitroomhq/postiz-app to v2.21.0 (#4924)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| ghcr.io/gitroomhq/postiz-app | minor | `v2.20.2` → `v2.21.0` |
| [gitroomhq/postiz-app](https://github.com/gitroomhq/postiz-app) | minor | `v2.20.2` → `v2.21.0` |

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> ⚠️ **Warning**
>
> Some dependencies could not be looked up. Check the [Dependency Dashboard](issues/2) for more information.

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### Release Notes

<details>
<summary>gitroomhq/postiz-app (gitroomhq/postiz-app)</summary>

### [`v2.21.0`](https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.0): MeWe Integration, Integration Fixes &amp; PR Quality

[Compare Source](https://github.com/gitroomhq/postiz-app/compare/v2.20.2...v2.21.0)

#### What's Changed

##### New Integration

- Added MeWe social media integration

##### Improvements

- Added PR Quality workflow for pull request checks

##### Fixes

- Fixed adding integrations flow
- Fixed OAuth integration connection handling

**Full Changelog**: <https://github.com/gitroomhq/postiz-app/compare/v2.20.2...v2.21.0>

</details>

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### Configuration

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♻ **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 these updates again.

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 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

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Reviewed-on: #4924
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Co-committed-by: Renovate Bot <renovate-bot@alexlebens.net>

clusters/cl01tl/helm/postiz/values.yaml

@@ -9,7 +9,7 @@ postiz:
         main:
           image:
             repository: ghcr.io/gitroomhq/postiz-app
-            tag: v2.20.2
+            tag: v2.21.0
             pullPolicy: IfNotPresent
           env:
             - name: MAIN_URL