Check { workspace = true, editable = false } support

[konstin]

We need to check the support of non-editable workspace dependencies in pyproject.toml. If it doesn't work remove it from the docs.

See also #5792.

[charliermarsh]

I've confirmed that this isn't supported. The issue is that we have to lock the entire workspace. So we add all the members (as editable), then lock, then install the appropriate subset.

In order to support this, I think we'd need to make editable part of dependencies, rather than its own source... Since we'd need the workspace member to be a directory that can either be installed as editable or non-editable.

[charliermarsh]

Do we want to support or remove? \cc @zanieb

[zanieb]

I guess we should remove it for now.

[charliermarsh]

I think I should make a timeboxed effort to fix it.