Make dependencies optional

## Driver version
2.0.908

## Problem description
In order to use the connecter, we have to pull in dependencies we don't need:

```
beautifulsoup4
lxml
scramp
soupsieve
```

This should be optional and not a requirement.

No files or tests are identified in the issue. Start by locating the project's dependency declarations and the connector entry points that import the listed packages, then determine which dependencies can be optional. Done means an installation for basic connector use no longer requires those packages.

索引モデルが issue の本文から書いたものです。