update to buildhub2

[willkg]

crash-stop-addon is currently using Buildhub:

crash-stop-addon/crashstop/buildhub.py

Line 14 in bcb5ae1

'https://buildhub.prod.mozaws.net/v1/buckets/build-hub/collections/releases/search'

Buildhub is deprecated and will be decommissioned in July. See mozilla-services/buildhub#532 for details.

There are API docs here:

https://buildhub2.readthedocs.io/en/latest/user.html

This issue covers migrating crash-stop-addon to Buildhub2.

[willkg]

I think crash-stop-addon needs to know about release candidates, so @calixteman wrote up this issue:

mozilla-releng/buildhub2#544

I turned around and wrote up this bug:

https://bugzilla.mozilla.org/show_bug.cgi?id=1553179

Is there anything else blocking buildhub2 from migrating? Is there any way to get around those issues?

[calixteman]

Fixed by 51be308