try out merge queues

[geekosaur]

Also enabling parallel checks, which should speed things up even more especially since Mergify forced us to separate the normal and squash-merge queues.

Also adjust the labels set for the bot to try to avoid making noise when it's being shoved straight in.

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Template B: This PR does not modify behaviour or interface

E.g. the PR only touches documentation or tests, does refactorings, etc.

Include the following checklist in your PR:

• Patches conform to the coding conventions.
• Is this a PR that fixes CI? If so, it will need to be backported to older cabal release branches (ask maintainers for directions). Mergify configuration is only read on master

[ulysses4ever]

If this works, that would be awesome! Only one way to find out...

[geekosaur]

BTW if this works then the next thing to try is to see if things we had to use merge+no rebase with work with merge me or squash+merge me. I think (per @TeofilC on Matrix) that Mergify cherry-picks commits into the queue PR, squashes them if it's the squash+merge queue, and rebases the result — which will be happening on Mergify's own local PR, not the one it's not allowed to rebase.

[ulysses4ever]

@geekosaur this sounds terrific, thank you for researching it! and thanks to @TeofilC for pitching in!

[Mikolaj]

Yay!