chore(deps): pin registry.mgrote.net/statping-ng docker tag to 6b00a9f (#687)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| registry.mgrote.net/statping-ng | pinDigest |  -> `6b00a9f` |

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### Configuration

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Reviewed-on: #687
Co-authored-by: Renovate Bot <renovate@mgrote.net>
Co-committed-by: Renovate Bot <renovate@mgrote.net>

docker-compose/statping-ng/docker-compose.yml.j2

@@ -3,7 +3,7 @@ version: '2.3'
 services:
   statping:
     container_name: statping
-    image: "registry.mgrote.net/statping-ng:latest"
+    image: "registry.mgrote.net/statping-ng:latest@sha256:6b00a9ff1560b66be71dc5afb74afe3336987b0ef46aad821fab8849e70768e7"
     restart: always
     volumes:
       - statping_data:/app