Bump dependencies (#4265)
<!-- CURSOR_SUMMARY -->
> [!NOTE]
> **Medium Risk**
> Dependency upgrades (especially `transformers` major version and
`weaviate-client` API shift) can introduce runtime or test regressions;
CI runner change may also surface environment-specific failures.
>
> **Overview**
> Bumps the release to `0.21.7` and updates dependency pins in
`pyproject.toml`, notably moving to `wrapt` 2.x+, `transformers` 5.x,
and `weaviate-client` 4.x (including constraint updates).
>
> Updates the Weaviate staging integration test to use the
`weaviate.connect_to_embedded()` / `collections.*` API instead of the
legacy `Client`/schema API. CI unit-test jobs are moved from
`ubuntu-latest` to the `opensource-linux-8core` runner, and `.gitignore`
now ignores `.venv*` directories.
>
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
8e265016243a2ff8227a9503c981f397f84ef09e. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->
