Change Node.reportinfo() return value from py.path to str|os.PathLike[str]

`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.

testing/python/collect.py

@@ -1154,8 +1154,8 @@ class TestReportInfo:
 
     def test_func_reportinfo(self, pytester: Pytester) -> None:
         item = pytester.getitem("def test_func(): pass")
-        fspath, lineno, modpath = item.reportinfo()
-        assert str(fspath) == str(item.path)
+        path, lineno, modpath = item.reportinfo()
+        assert os.fspath(path) == str(item.path)
         assert lineno == 0
         assert modpath == "test_func"
 
@@ -1169,8 +1169,8 @@ class TestReportInfo:
         )
         classcol = pytester.collect_by_name(modcol, "TestClass")
         assert isinstance(classcol, Class)
-        fspath, lineno, msg = classcol.reportinfo()
-        assert str(fspath) == str(modcol.path)
+        path, lineno, msg = classcol.reportinfo()
+        assert os.fspath(path) == str(modcol.path)
         assert lineno == 1
         assert msg == "TestClass"
 
@@ -1194,7 +1194,7 @@ class TestReportInfo:
         assert isinstance(classcol, Class)
         instance = list(classcol.collect())[0]
         assert isinstance(instance, Instance)
-        fspath, lineno, msg = instance.reportinfo()
+        path, lineno, msg = instance.reportinfo()
 
 
 def test_customized_python_discovery(pytester: Pytester) -> None:

testing/python/integration.py

@@ -19,7 +19,7 @@ class TestOEJSKITSpecials:
                     return MyCollector.from_parent(collector, name=name)
             class MyCollector(pytest.Collector):
                 def reportinfo(self):
-                    return self.fspath, 3, "xyz"
+                    return self.path, 3, "xyz"
         """
         )
         modcol = pytester.getmodulecol(
@@ -52,7 +52,7 @@ class TestOEJSKITSpecials:
                     return MyCollector.from_parent(collector, name=name)
             class MyCollector(pytest.Collector):
                 def reportinfo(self):
-                    return self.fspath, 3, "xyz"
+                    return self.path, 3, "xyz"
         """
         )
         modcol = pytester.getmodulecol(