docs: add pyyaml to requirements.txt (PaddlePaddle#903)

ceci3 · web-flow · commit 2550fb4ec86a · 2021-09-27T17:02:12.000+08:00
diff --git a/requirements.txt b/requirements.txt
@@ -4,3 +4,4 @@ pyzmq
 matplotlib
 opencv-python
 pillow 
+pyyaml
