Support workspaces by default

Unsure if this was intentional or not, but I was trying the `uv-lock` hook and thought it wasn't working and it was because of the `files` selector and I was editing a workspace `toml` file. This ended up working:

```yaml
- repo: https://github.com/astral-sh/uv-pre-commit
rev: 0.6.14
hooks:
- id: uv-lock
files: ^(uv\.lock|pyproject\.toml|uv\.toml|.*/pyproject\.toml)$
```

The bit I added was `|.*/pyproject\.toml` which may or may not be 100% right but it worked 😄

Start by reviewing the uv-lock hook configuration and its current files selector, then compare it with the workspace pyproject.toml pattern shown in the issue. Verify that the hook runs by default for workspace TOML files and check the existing hook behavior or tests for regressions.

Written by the indexing model from the issue text.