Remove TensorFlow Memmapped test file (#836)

test/models.json

@@ -5593,13 +5593,6 @@
     "format":   "TensorFlow Graph",
     "link":     "https://github.com/lutzroeder/netron/issues/187"
   },
-  {
-    "type":     "tf",
-    "target":   "deepspeech-0.9.3-models.pbmm",
-    "source":   "https://github.com/mozilla/DeepSpeech/releases/download/v0.9.3/deepspeech-0.9.3-models.pbmm",
-    "format":   "TensorFlow GraphDef Memmapped",
-    "link":     "https://github.com/lutzroeder/netron/issues/836"
-  },
   {
     "type":     "tf",
     "target":   "densenet.pb",