Don't wait to send GH updates on error/done

[icio]

There's a risk that the process will be killed while waiting.

[icio]

Haven't set up CI yet, so:

$ git log -1 --oneline
7e7a5ec (HEAD -> no-debounce-done, origin/no-debounce-done) Don't wait to send GH updates on error/done.

$ git status
On branch no-debounce-done
Your branch is up to date with 'origin/no-debounce-done'.

nothing to commit, working tree clean

$ go version
go version go1.19.5 linux/amd64


$ go test
PASS
ok      github.com/unravelin/gcb2gh     11.014s

[icio]

It looks like there's a further issue where we conclude the last-known build step is done but leave the commit status as pending: