Add missing test fixture

Author: jpic

dbdiff/tests/decimal_test/expected_no_reminder.json

@@ -0,0 +1,9 @@
+[
+{
+    "fields": {
+        "test_field": 10
+    },
+    "model": "decimal_test.testmodel",
+    "pk": 1
+}
+]

dbdiff/tests/test_mixin.json

@@ -55,12 +55,20 @@
     "model": "contenttypes.contenttype",
     "pk": 7
 },
+{
+    "fields": {
+        "app_label": "nonintpk",
+        "model": "nonintpk"
+    },
+    "model": "contenttypes.contenttype",
+    "pk": 8
+},
 {
     "fields": {
         "app_label": "",
         "model": ""
     },
     "model": "contenttypes.contenttype",
-    "pk": 8
+    "pk": 9
 }
 ]