Refine English README and Change Dependency Installation Method

[qidanrui]

This PR makes the following changes:

• Refine the English readme

• Change the installation method of DB-GPT-Hub from requirement.txt to poetry install, the advantages of Python Poetry includes:

  1. Prepare for building an automated workflow, which includes type checking, building, and testing that make it convenient to review and merge contributed PRs after thorough evaluation.

2. Convenient for adding and removing dependencies. For example, if you want to add a special version of black package, just run poetry add black==0.1.0. If you want to remove it, just run poetry remove black

3. Prepare for the automated releasing/publishing workflow to the PyPI (Python Package Index) and Package Repository of Anaconda

4. Enable automatic testing of our DB-GPT-Hub project on different Operating Systems and Python Environments.

• Refine code style with black
  • Just run poetry run black dbgpt_hub
• Ignore .vscode folder in .gitignore

[wangzaistone]

Great work !