proxy_pkey from in-memory also

[albundy83]

Is your feature request related to a problem? Please describe.
Following the update on pkey to be read from bytes, it will be nice to have proxy_pkey accepting the same behaviour.

Describe the solution you'd like
The same kind of behaviour than it works with pkey here since 2.8.0 #317

Describe alternatives you've considered
For moment, I don't have other alternative (or just ugly ones)

[pkittenis]

Hi there,

Thanks for the interest and report.

Yes, that would be good to add.

[pkittenis]

Provided in 2.10.0. Also supported via HostConfig.proxy_pkey.