config: stop using exception triplets in `ConftestImportError`

In recent python versions all of the info is on the exception object
itself so no reason to deal with the annoying tuple.

src/_pytest/config/__init__.py

@@ -17,7 +17,6 @@ from functools import lru_cache
 from pathlib import Path
 from textwrap import dedent
 from types import FunctionType
-from types import TracebackType
 from typing import Any
 from typing import Callable
 from typing import cast
@@ -112,16 +111,14 @@ class ConftestImportFailure(Exception):
     def __init__(
         self,
         path: Path,
-        excinfo: Tuple[Type[Exception], Exception, TracebackType],
+        *,
+        cause: Exception,
     ) -> None:
-        super().__init__(path, excinfo)
         self.path = path
-        self.excinfo = excinfo
+        self.cause = cause
 
     def __str__(self) -> str:
-        return "{}: {} (from {})".format(
-            self.excinfo[0].__name__, self.excinfo[1], self.path
-        )
+        return f"{type(self.cause).__name__}: {self.cause} (from {self.path})"
 
 
 def filter_traceback_for_conftest_import_failure(
@@ -152,7 +149,7 @@ def main(
         try:
             config = _prepareconfig(args, plugins)
         except ConftestImportFailure as e:
-            exc_info = ExceptionInfo.from_exc_info(e.excinfo)
+            exc_info = ExceptionInfo.from_exception(e.cause)
             tw = TerminalWriter(sys.stderr)
             tw.line(f"ImportError while loading conftest '{e.path}'.", red=True)
             exc_info.traceback = exc_info.traceback.filter(
@@ -654,8 +651,7 @@ class PytestPluginManager(PluginManager):
             mod = import_path(conftestpath, mode=importmode, root=rootpath)
         except Exception as e:
             assert e.__traceback__ is not None
-            exc_info = (type(e), e, e.__traceback__)
-            raise ConftestImportFailure(conftestpath, exc_info) from e
+            raise ConftestImportFailure(conftestpath, cause=e) from e
 
         self._check_non_top_pytest_plugins(mod, conftestpath)
 

src/_pytest/debugging.py

@@ -377,7 +377,8 @@ def _postmortem_traceback(excinfo: ExceptionInfo[BaseException]) -> types.Traceb
     elif isinstance(excinfo.value, ConftestImportFailure):
         # A config.ConftestImportFailure is not useful for post_mortem.
         # Use the underlying exception instead:
-        return excinfo.value.excinfo[2]
+        assert excinfo.value.cause.__traceback__ is not None
+        return excinfo.value.cause.__traceback__
     else:
         assert excinfo._excinfo is not None
         return excinfo._excinfo[2]

src/_pytest/nodes.py

@@ -384,7 +384,7 @@ class Node(abc.ABC, metaclass=NodeMeta):
         from _pytest.fixtures import FixtureLookupError
 
         if isinstance(excinfo.value, ConftestImportFailure):
-            excinfo = ExceptionInfo.from_exc_info(excinfo.value.excinfo)
+            excinfo = ExceptionInfo.from_exception(excinfo.value.cause)
         if isinstance(excinfo.value, fail.Exception):
             if not excinfo.value.pytrace:
                 style = "value"

testing/test_config.py

@@ -2108,9 +2108,7 @@ def test_conftest_import_error_repr(tmp_path: Path) -> None:
         try:
             raise RuntimeError("some error")
         except Exception as exc:
-            assert exc.__traceback__ is not None
-            exc_info = (type(exc), exc, exc.__traceback__)
-            raise ConftestImportFailure(path, exc_info) from exc
+            raise ConftestImportFailure(path, cause=exc) from exc
 
 
 def test_strtobool() -> None: