pip install coremltools onnx (#2690)

Requested in https://github.com/ultralytics/yolov5/issues/2686

Dockerfile

@@ -8,7 +8,7 @@ RUN apt update && apt install -y zip htop screen libgl1-mesa-glx
 COPY requirements.txt .
 RUN python -m pip install --upgrade pip
 RUN pip uninstall -y nvidia-tensorboard nvidia-tensorboard-plugin-dlprof
-RUN pip install --no-cache -r requirements.txt gsutil notebook
+RUN pip install --no-cache -r requirements.txt coremltools onnx gsutil notebook
 
 # Create working directory
 RUN mkdir -p /usr/src/app