chore(deps): update ghcr.io/traefik/traefik docker tag to v3.6.8 (#3934)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [ghcr.io/traefik/traefik](https://hub.docker.com/_/traefik) ([source](https://github.com/traefik/traefik-library-image)) | patch | `v3.6.7` → `v3.6.8` |

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### Release Notes

<details>
<summary>traefik/traefik-library-image (ghcr.io/traefik/traefik)</summary>

### [`v3.6.8`](https://github.com/traefik/traefik-library-image/compare/v3.6.8...v3.6.8)

[Compare Source](https://github.com/traefik/traefik-library-image/compare/v3.6.8...v3.6.8)

### [`v3.6.8`](https://github.com/traefik/traefik-library-image/compare/v3.6.7...v3.6.8)

[Compare Source](https://github.com/traefik/traefik-library-image/compare/v3.6.7...v3.6.8)

</details>

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Reviewed-on: #3934
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Co-committed-by: Renovate Bot <renovate-bot@alexlebens.net>

hosts/ps10rp/traefik/compose.yaml

@@ -20,7 +20,7 @@ services:
             - /dev/net/tun:/dev/net/tun
 
     traefik:
-        image: ghcr.io/traefik/traefik:v3.6.7
+        image: ghcr.io/traefik/traefik:v3.6.8
         container_name: traefik
         command:
             - "--global.checkNewVersion=false"