Fixes floors being silently discarded for old-style test layouts.
What was wrong
For a package using the old-style layout — test dependencies in [extras]/[weakdeps] plus [targets].test, with no test/Project.toml — the floors this action resolved were dropped before the tests ran.
The action folds [extras] into the merged [deps], min-resolves, and writes the floors to the project Manifest.toml. But Pkg.test does not run in the project environment: for an old-style layout it synthesizes a sandbox from [deps] plus the [targets].test names via Pkg.Operations.gen_target_project and resolves that fresh. A floor held only for a name reachable through [extras]/[weakdeps] never reached the sandbox, so it installed the newest compatible version instead. allow_reresolve: false did not prevent this.
The downgrade job therefore reported success while testing against current versions rather than the floors.
Impact
Minor rather than patch: downgrade jobs on old-style-layout packages that were passing may now legitimately fail, because they are testing the floors for the first time. That is the intended behaviour — a failure means the declared lower bounds do not actually work.
Consumers pinned to @v2 pick this up automatically.
See #57.