chore(build): update Mergify config

[mattgogerly]

The strict option is deprecated (brownout today). I think this config should be equivalent.

[christopherthielen]

oh nice, thanks! can you link to the mergify docs that explain these changes?

[mattgogerly]

oh nice, thanks! can you link to the mergify docs that explain these changes?

https://blog.mergify.com/strict-mode-deprecation/

I guess this CI won't succeed until the brownout finishes.

[dbyron-sf]

Yes, thanks much @mattgogerly! This is a big help.

[mattgogerly]

I'm unsure if the conditions in the queue config need to be duplicated in the main config like in the example. I'm hoping not..

I think this updated config will queue PRs once they're approved and have the appropriate label, then PRs in the queue will be checked sequentially for CI success and merged?

I wonder if having CI success as a condition for each block also would make sense.