Bugbear must be selected

Implement this [repo-review](https://learn.scientific-python.org/development/guides/repo-review/?repo=populse%2Fcapsul&branch=3.0) recommendation:

[RF101](https://learn.scientific-python.org/development/guides/style#RF101): Bugbear must be selected
Must select the flake8-bugbear `B` checks. Recommended:
```
[tool.ruff.lint]
extend-select = [
  "B",  # flake8-bugbear
]
```