Bump dropshot from 1da9d81 to a606966

Bumps [dropshot](https://github.com/oxidecomputer/dropshot) from `1da9d81` to `a606966`.
- [Release notes](https://github.com/oxidecomputer/dropshot/releases)
- [Commits](oxidecomputer/dropshot@1da9d81...a606966)

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

Signed-off-by: dependabot[bot] <[email protected]>