remove blockchain stream timeout

[yusefnapora]

this uses with / as to open the canonical_stream from the transactor, and defaults to setting timeout=None so we get an infinite stream of events. It will still close cleanly if you ctrl-c the process, etc.

[yusefnapora]

we should wait a second to merge this; I need to push up a new client package, and we can update the dependency here

[parkan]

lgtm