fix: runner url in contributing.md

[pfiaux]

I had this strange error trying to run the runner for a PR:

15:56:33.469	error	failed to connect	{"error": "dial tcp: lookup github.bass-loop.org on ....1:53: no such host"}
dial: 1 error occurred:
	* dial tcp: lookup github.bass-loop.org on ...1:53: no such host

Looks like the url wasn't correct in the example.

[vito]

Whoops, nice catch. Thanks!

Not sure why all the builds failed for this. Was the bass --runner command terminated in the middle of it? Either way this is obviously OK to merge so I'll go ahead and do that.

[pfiaux]

I had the runner in the foreground, when I realized it wasn't going to pickup the commits from #242 I killed it without realizing it was running these. If I remember correctly the output only shows the health checks/keep alive pings from the server, but I didn't see any "currently running ..." so I didn't realize it was running jobs 😬.

[vito]

Yeah true, I've been thinking of having it show all the output for everything it's running. It's definitely a bit too quiet.