remove un-used imported modules, so to avoid PyInstaller packaged binary runtime error

[kerneltravel]

by current PR, remove un-used imported modules in code, so to avoid PyInstaller packaged binary 's py-script import them, which in fact is not included by pyinstaller when package.

if not merge current PR , then PyInstaller should add parameter --hidden-import imghdr --hidden-import scipy.io and must add parameter --collect-all paddleocr , but the previous parameter is not suggested to hidden-import un-used modules for package release.

Previously there is a commit has Improve package import compatibility of paddleocr.py file. but the pyinstaller packaged execution file runtime not found module issue still exists.

I had tried another PR #10421 ,but that is not the root cause.

history:

1. the related issues ID No module named 'tools.infer'  #1024 使用Pyinstaller将PPOCRLabel.py打包成exe文件时遇到No module named 'framework_pb2'的报错。官方是不是有一个打包工具的，这个工具文档在哪里？ #9355 ModuleNotFoundError: No module named 'tools' #10398, Pyinstaller - no module named "ppocr" #10340, Pyinstaller exe problem #9951, hubserving运行。服务调用。多调用几次会报找不到tools包。整个hubserving当掉 #9723 ModuleNotFoundError: No module named 'tools' #9694, Pyinstall related problem #9944, 给各位老总一个建议，关于大家用pyinstaller打包exe会出现各种ModuleNotFoundError: No module named 'XXXX' #9408 , 使用pyinstaller打包成可执行文件报错 #7635, 用Pyinstaller构建可执行程序 No module name 'tools' #4390
2. how to reproduce the above issue: https://github.com/kerneltravel/PaddleOCR_PR10421_reproduce/blob/1ed3c8211ca07f9779c10e07dfbfcf81466ddfd5/README.md

NOTE: those people who want to use pyinstaller to package python-application with paddleocr may referer to this to append parameter --collect-all paddleocr to pyinstaller . --collect-all MODULE_NAMES means Collect all submodules, data files, and binaries from the specified package or module.

[paddle-bot]

Thanks for your contribution!

[shiyutang]

LGTM

[shiyutang]

Thank you very much for your contribution, please cherry-pick this commit to the dygraph branch as well. :)

[kerneltravel]

@shiyutang 要求怎样做？

Thank you very much for your contribution, please cherry-pick this commit to the dygraph branch as well. :)