(deps) fix issue w/ compiling smolboi
This is very strange: `smolboi` was able to be compiled when invoking
`cargo build` at the workspace root, but not from within its own member
root. The issue is that `AsyncReadExt` and `AsyncWriteExt` were not
being resolved. To compound the strangeness: `rusct-analyzer` in my
editor (a) did not show that `use` line as an error, and even helped
auto-complete it.
The issue, it turns out, is that in the latest version fo `futures-util`
has these traits behind a feature flag. I am not sure why that feature
flag seems to have no effect on the workspace root, but here we are.