MiddlewareListener namespace update for new version of Interop\Http\MiddlewareInterface

[yurivecchi]

Hi!

As http-interop/http=middleware updated their code to comply with PSR-15 changes, MiddlewareListener doesn't got updated to follow the new namespace, only necessary change is the import from:

use Interop\Http\ServerMiddleware\MiddlewareInterface;

to:

use Interop\Http\Server\MiddlewareInterface;

and all keeps working.

I can do the PR or you will wait for the PSR to be approved?

[froschdesign]

Interop\Http\Server\MiddlewareInterface is deprecated in favor of PSR-15.

See also: #259 – open for comments!