Updating gitmodules - new TRT version for BERT/TF

.gitmodules

@@ -4,7 +4,7 @@
 [submodule "TensorFlow/LanguageModeling/BERT/tensorrt-inference-server"]
     path = TensorFlow/LanguageModeling/BERT/tensorrt-inference-server
     url = https://github.com/NVIDIA/tensorrt-inference-server.git
-    branch = r19.06
+    branch = r19.08
 [submodule "PyTorch/SpeechRecognition/Jasper/external/tensorrt-inference-server"]
     path = PyTorch/SpeechRecognition/Jasper/external/tensorrt-inference-server
     url = https://github.com/NVIDIA/tensorrt-inference-server.git