Add a consistent single-item array to catch more possible edge cases

Author: kpaulisse

spec/octocatalog-diff/fixtures/catalogs/filter-single-item-array-1.json

@@ -36,7 +36,10 @@
             "Service[foo]",
             "Service[bar]"
           ],
-          "owner": "root"
+          "owner": "root",
+          "subscribe": [
+            "Service[baz]"
+          ]
         }
       },
       {

spec/octocatalog-diff/fixtures/catalogs/filter-single-item-array-2.json

@@ -38,7 +38,10 @@
             "Service[foo]",
             "Service[baz]"
           ],
-          "owner": "root"
+          "owner": "root",
+          "subscribe": [
+            "Service[baz]"
+          ]
         }
       },
       {