Change default provenance to true (#59)

Docker build workflow default parameter provenance now set to `true`

Author: tcarmet

.github/workflows/docker-build.yaml

@@ -51,7 +51,7 @@ on:
       provenance:
         required: false
         type: boolean
-        default: false
+        default: true
     secrets:
       REGISTRY_LOGIN:
         required: false