update requirements.txt

ppstructure/README.md

@@ -36,7 +36,7 @@ python3 -m pip install paddlepaddle-gpu==2.1.1 -i https://mirror.baidu.com/pypi/
 - **(2) Install Layout-Parser**
 
 ```bash
-pip3 install -U premailer paddleocr https://paddleocr.bj.bcebos.com/whl/layoutparser-0.0.0-py3-none-any.whl
+pip3 install -U https://paddleocr.bj.bcebos.com/whl/layoutparser-0.0.0-py3-none-any.whl
 ```
 
 ### 2.2 Install PaddleOCR（including PP-OCR and PP-Structure）

ppstructure/README_ch.md

@@ -36,7 +36,7 @@ python3 -m pip install paddlepaddle-gpu==2.1.1 -i https://mirror.baidu.com/pypi/
 - **(2) 安装 Layout-Parser**
 
 ```bash
-pip3 install -U premailer paddleocr https://paddleocr.bj.bcebos.com/whl/layoutparser-0.0.0-py3-none-any.whl
+pip3 install -U https://paddleocr.bj.bcebos.com/whl/layoutparser-0.0.0-py3-none-any.whl
 ```
 
 ### 2.2 安装PaddleOCR（包含PP-OCR和PP-Structure）

requirements.txt

@@ -8,3 +8,5 @@ numpy
 visualdl
 python-Levenshtein
 opencv-contrib-python==4.2.0.32
+lxml
+premailer
\ No newline at end of file