flake: add remaining drvs to ci.buildbot

[0xda157]

Closes: https://github.com/nix-community/stylix/issues/2056

---

• [x] I certify that I have the right to submit this contribution under the MIT license
• [x] Commit messages adhere to Stylix commit conventions
• [ ] Theming changes adhere to the Stylix style guide
• [ ] Changes have been tested locally
• [ ] Changes have been tested in testbeds
• [x] Each commit in this PR is suitable for backport to the current stable branch