Fixed classify and nsfw tests

They were broken when the constructors changed to include metadata.

internal/ai/classify/model_test.go

@@ -224,7 +224,7 @@ func TestModel_LoadModel(t *testing.T) {
 		err := tensorFlow.loadModel()
 
 		if err != nil {
-			assert.Contains(t, err.Error(), "no such file or directory")
+			assert.Contains(t, err.Error(), "Could not find SavedModel")
 		}
 
 		assert.Error(t, err)