requirements.txt is outdated

The contents of the current `requirements.txt` seem to be outdated. The contents are as follows:
```
certifi==2019.6.16
chardet==3.0.4
idna==2.8
requests==2.22.0
urllib3==1.26.5
```

The `rich` library is now used in the program which is not specified as part of `requirements.txt`.

Start with requirements.txt and compare its entries with the program's current imports, especially the use of rich. Update the dependency list so a clean environment can install everything the program needs, then verify that installation and a basic program run succeed.

索引モデルが issue の本文から書いたものです。