Merge master (#555)

* Revisit Floodsub (#543)

Fixes #525

add coverage to unsubscribeAll and testing

* add mounted protos to identify message (#546)

* add stable/unstable auto bumps

* fix auto-bump CI

* merge nbc auto bump with CI in order to bump only on CI success

* put conditional locks on nbc bump (#549)

* Fix minor exception issues (#550)

Makes code compatible with
status-im/nim-chronos#166 without requiring it.

* fix nimbus ref for auto-bump stable's PR

* Split dialer (#542)

* extracting dialing logic to dialer

* exposing upgrade methods on transport

* cleanup

* fixing tests to use new interfaces

* add comments

* add base exception class and fix hierarchy

* fix imports

* `doAssert` is `ValueError` not `AssertionError`?

* revert back to `AssertionError`

Co-authored-by: Giovanni Petrantoni <7008900+sinkingsugar@users.noreply.github.com>
Co-authored-by: Jacek Sieka <jacek@status.im>