Fix the shell in crane image

The auth step in the publish task uses /busybox/sh in the crane
image but that does not exists anymore, switch to /bin/sh

Signed-off-by: Andrea Frittoli <andrea.frittoli@uk.ibm.com>

tekton/publish.yaml

@@ -63,7 +63,7 @@ spec:
   - name: container-registry-auth
     image: cgr.dev/chainguard/crane:latest-dev@sha256:a91db0ec686127bf25698bc102c8d887437b6717b7df15570e70927fdbf7bcc5
     script: |
-      #!/busybox/sh
+      #!/bin/sh
       set -ex
 
       # Login to the container registry