chore(deps): update gitroomhq/postiz-app to v2.15.0 (#3843)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| ghcr.io/gitroomhq/postiz-app | minor | `v2.14.0` → `v2.15.0` |
| [gitroomhq/postiz-app](https://github.com/gitroomhq/postiz-app) | minor | `v2.14.0` → `v2.15.0` |

---

### Release Notes

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

### [`v2.15.0`](https://github.com/gitroomhq/postiz-app/releases/tag/v2.15.0): New Concept: Providers with a chrome extension - Skool

[Compare Source](https://github.com/gitroomhq/postiz-app/compare/v2.14.0...v2.15.0)

What I love about this project is that I can just "do things". We have now added an option to schedule posts on Skool.
The way it works: you install the Postiz Chrome extension, log in to Skool, and add it. It will save (encrypted) your Skool cookies and use their internal API. Please be advised that, since we don't use their official API, your account may be suspended; use it at your own risk.

With the new Chrome extension compatibility, we will work to add more platforms, such as Substack.

What else?

- Bluesky connection fixes
- Add a new funny provider - Moltbook
- WordPress fixes

And we have our first big sponsor: Hostinger, Yay!

**Full Changelog**: <https://github.com/gitroomhq/postiz-app/compare/v2.14.0...v2.15.0>

</details>

---

### Configuration

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

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

♻ **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.

---

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

---

This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0My4zLjYiLCJ1cGRhdGVkSW5WZXIiOiI0My4zLjYiLCJ0YXJnZXRCcmFuY2giOiJtYWluIiwibGFiZWxzIjpbImltYWdlIl19-->

Reviewed-on: #3843
Co-authored-by: Renovate Bot <renovate-bot@alexlebens.net>
Co-committed-by: Renovate Bot <renovate-bot@alexlebens.net>

clusters/cl01tl/helm/postiz/Chart.yaml

@@ -41,4 +41,4 @@ dependencies:
     repository: oci://harbor.alexlebens.net/helm-charts
 icon: https://cdn.jsdelivr.net/gh/selfhst/icons/png/postiz.png
 # renovate: datasource=github-releases depName=gitroomhq/postiz-app
-appVersion: v2.14.0
+appVersion: v2.15.0

clusters/cl01tl/helm/postiz/values.yaml

@@ -9,7 +9,7 @@ postiz:
         main:
           image:
             repository: ghcr.io/gitroomhq/postiz-app
-            tag: v2.14.0
+            tag: v2.15.0
             pullPolicy: IfNotPresent
           env:
             - name: MAIN_URL