ci: Try to pin images

Signed-off-by: Joas Schilling <coding@schilljs.com>

.github/workflows/phpunit-object-store-primary.yml

@@ -6,6 +6,9 @@ on:
   schedule:
     - cron: "15 2 * * *"
 
+permissions:
+  contents: read
+
 concurrency:
   group: phpunit-object-store-primary-${{ github.head_ref || github.run_id }}
   cancel-in-progress: true
@@ -54,13 +57,13 @@ jobs:
 
     services:
       cache:
-        image: ghcr.io/nextcloud/continuous-integration-redis:latest
+        image: ghcr.io/nextcloud/continuous-integration-redis:latest # zizmor: ignore[unpinned-images]
         ports:
           - 6379:6379/tcp
         options: --health-cmd="redis-cli ping" --health-interval=10s --health-timeout=5s --health-retries=3
 
       minio:
-        image: bitnami/minio
+        image: bitnami/minio@sha256:50cec18ac4184af4671a78aedd5554942c8ae105d51a465fa82037949046da01 # v2025.4.22
         env:
           MINIO_ROOT_USER: nextcloud
           MINIO_ROOT_PASSWORD: bWluaW8tc2VjcmV0LWtleS1uZXh0Y2xvdWQ=
@@ -70,8 +73,9 @@ jobs:
 
     steps:
       - name: Checkout server
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
+          persist-credentials: false
           submodules: true
 
       - name: Set up php ${{ matrix.php-versions }}