Bump version of the Ruby extension to 0.0.8.

Changes:

- https://github.com/zed-industries/zed/pull/12642
- https://github.com/zed-industries/zed/pull/13216
- https://github.com/zed-industries/zed/pull/14661
- https://github.com/zed-industries/zed/pull/14693

Release Notes:

- N/A