Docker pyYAML>=5.3.1 fix (#2031)

Dockerfile

@@ -5,7 +5,7 @@ FROM nvcr.io/nvidia/pytorch:20.12-py3
 RUN apt update && apt install -y screen libgl1-mesa-glx
 
 # Install python dependencies
-RUN pip install --upgrade pip
+RUN python -m pip install --upgrade pip
 COPY requirements.txt .
 RUN pip install -r requirements.txt gsutil
 

requirements.txt

@@ -6,7 +6,7 @@ matplotlib>=3.2.2
 numpy>=1.18.5
 opencv-python>=4.1.2
 Pillow
-PyYAML==5.4.1
+PyYAML>=5.3.1
 scipy>=1.4.1
 tensorboard>=2.2
 torch>=1.7.0