Remove unnecessary assertions in `RedisCommandHandler`

Motivation:

The assertions in errorCaught(context:error:) and channelRead(context:data:) are holdovers from when SwiftLog was not integrated into the package. The conditions where they were triggered are safely handled in other ways, so the asserts are not guarding against undefined behavior or bad app state.

Modifications:

Remove the two asserts regarding the RedisCommandHandler.commandResponseQueue to rely on Logging to bubble up errors to the user.

Result:

Debug builds using RediStack should not encounter unexpected assertions and should rely on other, better, error handling.

This contributes to issue #65 (closed)