Pin MinIO in Docker Compose config (#2900)

CI jobs recently started
[failing](https://github.com/Kitware/CDash/actions/runs/15325557396/job/43119066230)
due to a recent MinIO image update. This PR pins MinIO to the previous
working version until we resolve the issue with the latest version.

Author: williamjallen

docker/docker-compose.minio.yml

@@ -10,7 +10,7 @@ services:
       AWS_URL: http://minio:9000/cdash/
       AWS_ENDPOINT: http://minio:9000
   minio:
-    image: bitnami/minio:latest
+    image: bitnami/minio:2025.4.22
     ports:
       - "9000:9000"
     environment: