We're currently depending on a floating "latest", which is often a bad
idea. Today my machine decided to upgrade the google plugin,w hich is no
specifying some new fields for the GCS objects, and therefore `terraform
plan` doe snot look clean anymore, even though there has been no change
to the terraform files (nor to the infrastructure).
This PR aims to make our Terraform setup more reproducible by pinning
Terraform plugin versions. It's also a way to track the application of
the "new" Terraform setup, as it is technically a standard change
(though hopefully a very safe one).
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* nix: add the more providers to terraform
* docs: make tarballs more reproducible
* ci: use the linux-pool pool
* ci: tweak the nix installation
handle the case where the user is root and on ubuntu
* infra: terraform fmt
* infra: add Azure Pipeline agents
* ci: only enable linux-pool for internal PRs