Add a light/minimal installation option

I'd like to use some of the "base" fetch features of fetchcode without having to introduce the whole stack of dependencies (over 20...) in my projects.

```
$ pip install fetchcode

Installing collected packages: webencodings, text_unidecode, fusepy, urllib3, typing-extensions, soupsieve, six, PyYAML, python-dotenv, packageurl-python, idna, click, charset_normalizer, chardet, certifi, attrs, saneyaml, requests, python-dateutil, html5lib, Beautifulsoup4, htmllistparse, commoncode, fetchcode

Successfully installed Beautifulsoup4-4.14.3 PyYAML-6.0.3 attrs-25.4.0 certifi-2025.11.12 chardet-5.2.0 charset_normalizer-3.4.4 click-8.3.1 commoncode-32.4.0 fetchcode-0.8.0 fusepy-3.0.1 html5lib-1.1 htmllistparse-0.6.1 idna-3.11 packageurl-python-0.17.6 python-dateutil-2.9.0.post0 python-dotenv-1.2.1 requests-2.32.5 saneyaml-0.6.1 six-1.17.0 soupsieve-2.8 text_unidecode-1.3 typing-extensions-4.15.0 urllib3-2.5.0 webencodings-0.5.1
```

Could we consider a "minimal"/"lightweight" installation option?