Update deps for Dome: use msgs6, transport9

[j-rivero]

As part of the works of gazebo-tooling/gazebodistro#5 bump the use of msgs to major version 6 and transport to 9

[j-rivero]

CI is going to need gazebosim/gz-transport#149 and osrf/homebrew-simulation#1063 for Brew

[chapulina]

Good to go once CI and deps are in.

[chapulina]

CI results:

• Jenkins Ubuntu has more errors than expected, with lots of errors that "Could not connect to any X display." @j-rivero , do we need to mark ign-gui CI with some label that requires X?
• OSX and Windows don't have any new failures
• Actons is failing because libignition-transport9-dev is not released on Bionic for nightlies.

[j-rivero]

@osrf-jenkins run tests please

[j-rivero]

CI results:

* Jenkins Ubuntu has more errors than expected, with lots of errors that "_Could not connect to any X display._" @j-rivero , do we need to mark `ign-gui` CI with some label that requires X?

It was a temporary problem on the node, is passing now.

* Actons is failing because `libignition-transport9-dev` is not released on Bionic for nightlies.

Released today. I've rerun the actions but they are failing because the tests need a GUI display I think.

[chapulina]

@osrf-jenkins run tests please

[chapulina]

I've rerun the actions but they are failing because the tests need a GUI display I think.

Yup, I tried something similar to gazebosim/gz-rendering#115 but it didn't help. I guess we can merge this an follow up on this issue: #58