always cache minio & garage binaries

they are sometime very slow to download and it does not help to do it
five times for each workflow

.forgejo/prepare-end-to-end/action.yml

@@ -1,6 +1,16 @@
 runs:
   using: "composite"
   steps:
+      - name: cache S3 binaries
+        id: S3
+        uses: https://code.forgejo.org/actions/cache@v3
+        with:
+          path: |
+            /usr/local/bin/minio
+            /usr/local/bin/mc
+            /usr/local/bin/garage
+          key: S3
+
       - uses: https://code.forgejo.org/actions/setup-forgejo@v2
         with:
           install-only: true