Bump dropshot from ab0194f to 115dd34 (#959)

Bumps [dropshot](https://github.com/oxidecomputer/dropshot) from `ab0194f` to `115dd34`.
- [Commits](oxidecomputer/dropshot@ab0194f...115dd34)

---
updated-dependencies:
- dependency-name: dropshot
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>