Migrate to modern bs4 interface (#4025)
## PR Summary
This small PR fixes the bs4 deprecation warnings which you can find in
the [CI
logs](https://github.com/Unstructured-IO/unstructured/actions/runs/15491657572/job/43729960936#step:3:2615):
```python
/app/unstructured/metrics/table/table_extraction.py:53: DeprecationWarning: Call to deprecated method findAll. (Replaced by find_all) -- Deprecated since version 4.0.0.
/app/unstructured/metrics/table/table_extraction.py:57: DeprecationWarning: Call to deprecated method findAll. (Replaced by find_all) -- Deprecated since version 4.0.0.
```
---------
Signed-off-by: Emmanuel Ferdman <emmanuelferdman@gmail.com>
