(hacky) update embedded-io to 0.5

[kbleeke]

I realize there is already discussion and plans to address this in #39 but I had the urge to update my hobby embassy project now: ;)

I'm still posting it, in case someone finds it useful

I mostly propagate WriteAllError or collapse it down to embedded_io::ErrorKind when that's not an option.

[lulf]

First of all thanks for doing the effort. I think we should just merge this for now, even if it's as you say a little hacky. The alternative is not being useable with later embassy versions for some time.

@rmja @bugadani Wdyt?

[bugadani]

No objections, there's very little point in waiting for future changes to happen. We will be able to revert this in whole or in parts if the WriteAllError stuff gets removed. Worst case, the 0.7 version of reqwless will be short lived and very specific in what portion of the embedded ecosystem it works with.

[lulf]

Released as 0.7.0