update opencv-python version

doc/COMPILE.md

@@ -23,7 +23,7 @@
 |           libXext            |                            1.3.3                             |
 |            libSM             |                            1.2.2                             |
 |          libXrender          |                            0.9.10                            |
-|          python-whl          | numpy>=1.12, <=1.16.4<br/>wheel>=0.34.0, <0.35.0<br/>setuptools>=44.1.0<br/>opencv-python==4.2.0.32<br/>google>=2.0.3<br/>protobuf>=3.12.2<br/>grpcio-tools>=1.28.1<br/>grpcio>=1.28.1<br/>func-timeout>=4.3.5<br/>pyyaml>=1.3.0<br/>sentencepiece==0.1.92<br>flask>=1.1.2<br>ujson>=2.0.3 |
+|          python-whl          | numpy>=1.12, <=1.16.4<br/>wheel>=0.34.0, <0.35.0<br/>setuptools>=44.1.0<br/>opencv-python==4.2.0.32, <4.4.0.40<br/>google>=2.0.3<br/>protobuf>=3.12.2<br/>grpcio-tools>=1.28.1<br/>grpcio>=1.28.1<br/>func-timeout>=4.3.5<br/>pyyaml>=1.3.0<br/>sentencepiece==0.1.92<br>flask>=1.1.2<br>ujson>=2.0.3 |
 
 It is recommended to use Docker for compilation. We have prepared the Paddle Serving compilation environment for you, see [this document](DOCKER_IMAGES.md).
 

doc/COMPILE_CN.md

@@ -23,7 +23,7 @@
 |           libXext            |                            1.3.3                             |
 |            libSM             |                            1.2.2                             |
 |          libXrender          |                            0.9.10                            |
-|          python-whl          | numpy>=1.12, <=1.16.4<br/>wheel>=0.34.0, <0.35.0<br/>setuptools>=44.1.0<br/>opencv-python==4.2.0.32<br/>google>=2.0.3<br/>protobuf>=3.12.2<br/>grpcio-tools>=1.28.1<br/>grpcio>=1.28.1<br/>func-timeout>=4.3.5<br/>pyyaml>=1.3.0<br/>sentencepiece==0.1.92<br/>flask>=1.1.2<br/>ujson>=2.0.3 |
+|          python-whl          | numpy>=1.12, <=1.16.4<br/>wheel>=0.34.0, <0.35.0<br/>setuptools>=44.1.0<br/>opencv-python==4.2.0.32, <4.4.0.40<br/>google>=2.0.3<br/>protobuf>=3.12.2<br/>grpcio-tools>=1.28.1<br/>grpcio>=1.28.1<br/>func-timeout>=4.3.5<br/>pyyaml>=1.3.0<br/>sentencepiece==0.1.92<br/>flask>=1.1.2<br/>ujson>=2.0.3 |
 
 推荐使用Docker编译，我们已经为您准备好了Paddle Serving编译环境，详见[该文档](DOCKER_IMAGES_CN.md)。
 

python/requirements.txt

 numpy>=1.12, <=1.16.4 ; python_version<"3.5"
 wheel>=0.34.0, <0.35.0
 setuptools>=44.1.0
-opencv-python==4.2.0.32
+opencv-python==4.2.0.32, <4.4.0.40
 google>=2.0.3
 protobuf>=3.12.2
 grpcio-tools>=1.28.1