Docker Compose: Bump linuxserver/ffmpeg in /tests/perf_tests/compose

Bumps linuxserver/ffmpeg from version-8.0.1-cli to version-8.1-cli.

---
updated-dependencies:
- dependency-name: linuxserver/ffmpeg
  dependency-version: version-8.1-cli
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

tests/perf_tests/compose/docker-compose-inference_performance.yml

@@ -60,7 +60,7 @@ services:
     pids_limit: 1000
 
   retail-cams:
-    image: linuxserver/ffmpeg:version-8.0.1-cli
+    image: linuxserver/ffmpeg:version-8.1-cli
     command: |
       -nostdin
       -re -stream_loop -1 -i /workspace/media/apriltag-cam1.ts