Fix USubscription doc tests

[sophokles73]

The doc tests had not been updated yet to reflect the changes
introduced to the UTransport trait's functions for matching on
source and sink address patterns.

[PLeVasseur]

LGTM

@sophokles73 -- does that mean the doc tests didn't catch this and fail the build when the UTransport::register_listener() change went in?

[sophokles73]

LGTM

@sophokles73 -- does that mean the doc tests didn't catch this and fail the build when the UTransport::register_listener() change went in?

At least not as part of the tests we run in our standard CI build. That is because that standard build does not activate the usubscription feature, but the nightly build does :-)

[AnotherDaniel]

This is interesting insofar as I'd expect the --all-features flag to enable, well, all features?

[sophokles73]

This is interesting insofar as I'd expect the --all-features flag to enable, well, all features?

@AnotherDaniel
Doc tests are not (yet) supported in cargo nextest:
nextest-rs/nextest#16

Maybe you can add an extra cargo test --doc step to the corresponding job?