`reportinfo()` is the last remaining py.path-only code path in pytest,
i.e. the last piece holding back py.path deprecation. The problem with
it is that plugins/users use it from both sides -- implementing it
(returning the value) and using it (using the return value). Dealing
with implementers is easy enough -- allow to return `os.PathLike[str]`.
But for callers who expect strictly `py.path` this will break and
there's not really a good way to provide backward compat for this.
From analyzing a corpus of 680 pytest plugins, the vast majority of
`reportinfo` appearances are implementations, and the few callers don't
actually access the path part of the return tuple.
As for test suites that might access `reportinfo` (e.g. using
`request.node.reportinfo()` or other ways), that is much harder to
survey, but from the ones I searched, I only found case
(`pytest_teamcity`, but even then it uses `str(fspath)` so is unlikely
to be affected in practice). They are better served with using
`node.location` or `node.path` directly.
Therefore, just break it and change the return type to
`str|os.PathLike[str]`.
Refs #7259.
7eee5c1634