Update requirements.txt

[dongrixinyu]

The lib markupsafe has deprecated the method soft_unicode since 2.1.0. So 2.0.1 version is recommended.

It will cause the error below:

    from .debug import traceback_response
  File "/home/ubuntu/anaconda3/lib/python3.8/site-packages/quart/debug.py", line 6, in <module>
    from jinja2 import Template
  File "/home/ubuntu/anaconda3/lib/python3.8/site-packages/jinja2/__init__.py", line 12, in <module>
    from .environment import Environment
  File "/home/ubuntu/anaconda3/lib/python3.8/site-packages/jinja2/environment.py", line 25, in <module>
    from .defaults import BLOCK_END_STRING
  File "/home/ubuntu/anaconda3/lib/python3.8/site-packages/jinja2/defaults.py", line 3, in <module>
    from .filters import FILTERS as DEFAULT_FILTERS  # noqa: F401
  File "/home/ubuntu/anaconda3/lib/python3.8/site-packages/jinja2/filters.py", line 13, in <module>
    from markupsafe import soft_unicode
ImportError: cannot import name 'soft_unicode' from 'markupsafe' (/home/ubuntu/anaconda3/lib/python3.8/site-packages/markupsafe/__init__.py)

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[dongrixinyu]

I have signed the CLA. Thank you

[wj-Mcat]

I have signed the CLA. Thank you

thansk for your improvement.

[wj-Mcat]

There are some errors in ci, can you try to fix it. Thanks city you later commit.