update preflight sha for 1.15.2 release (#867)

Signed-off-by: Adam D. Cornett <adc@redhat.com>

Author: acornett21

ansible/roles/operator-pipeline/templates/openshift/tasks/preflight.yml

@@ -7,7 +7,7 @@ spec:
   params:
     - name: pipeline_image
     - name: base_image
-      default: quay.io/redhat-isv/preflight-test@sha256:57f74e3d1ad72bfd11cf888eae99f8cad4d75c25515413a7c30ad9963aed2741
+      default: quay.io/redhat-isv/preflight-test@sha256:6e857a015829a53e2139b3f857816c91ff9bf0b37a44d4e473ad92f8b878c1c9
       description: Preflight image used
     - name: bundle_index_image
       description: The Operator index image which includes the bundle