Update nextflow_schema.json

nextflow_schema.json

@@ -93,7 +93,6 @@
             "properties": {
                 "digestion": {
                     "type": "string",
-                    "default": null,
                     "description": "Name of restriction enzyme to automatically set the restriction_site and ligation_site options (hindiii, mboi, dpnii, arima)",
                     "enum": ["hindiii", "mboi", "dpnii", "arima"]
                 },