Revert cysignals build constraint

[tobiasdiez]

Reverts 95428a1 which broke the conda ci.

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

[dimpase]

lgtm

[github-actions]

Documentation preview for this PR (built with commit 0166cab; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[tobiasdiez]

Thanks @dimpase for the quick review. Tests are passing (Conda (macos-latest) failure is already there in main branch) > marking as ci fix to directly apply to other PRs as well.

[mkoeppe]

One does not revert without doing due diligence on why the change was made etc.

[dimpase]

the changes by @mkoeppe were not taking into account the needs of sagelib package maintainers, that's why parts of them need to be reversed

[roed314]

We have set this PR to disputed; participants may set it to positive review by counting votes in accordance with the disputed PR policy.
The Sage Code of Conduct Committee

[tobiasdiez]

There doesn't seem to be any need for further discussions. Setting this to positive review due to
+1: @dimpase, me
-1: @mkoeppe (perhaps)