gnu: python-pytest: Fix failing test_raising_repr.

* gnu/packages/patches/pytest-fix-unstrable-exception-test.patch: Add new
patch from upstream.
* gnu/packages/check.scm (python-pytest): Use it.
* gnu/local.mk (dist_patch_DATA): Register it.

Signed-off-by: Andreas Enge <andreas@enge.fr>

gnu/packages/patches/pytest-fix-unstrable-exception-test.patch

@@ -0,0 +1,34 @@
+From b55e264a675f7621b8351e227b93742f19e01c7d Mon Sep 17 00:00:00 2001
+From: Daniel Valenzuela <dsvalenzuela@uc.cl>
+Date: Wed, 9 Nov 2022 19:43:10 -0300
+Subject: [PATCH] Fix test_raising_repr test
+
+Closes #10473
+
+Python <3.11 versions depend on `exceptiongroup>=1.0.0rc8`, and they released version `1.0.1`
+6 days ago (2022/11/03) that as a side-effect changed the output of exceptions.
+---
+ testing/test_assertion.py | 10 +---------
+ 1 file changed, 1 insertion(+), 9 deletions(-)
+
+diff --git a/testing/test_assertion.py b/testing/test_assertion.py
+index d8844f2e41..7574592210 100644
+--- a/testing/test_assertion.py
++++ b/testing/test_assertion.py
+@@ -1664,15 +1664,7 @@ def test_raising_repr():
+     """
+     )
+     result = pytester.runpytest()
+-    if sys.version_info >= (3, 11):
+-        # python 3.11 has native support for un-str-able exceptions
+-        result.stdout.fnmatch_lines(
+-            ["E       AssertionError: <exception str() failed>"]
+-        )
+-    else:
+-        result.stdout.fnmatch_lines(
+-            ["E       AssertionError: <unprintable AssertionError object>"]
+-        )
++    result.stdout.fnmatch_lines(["E       AssertionError: <exception str() failed>"])
+ 
+ 
+ def test_issue_1944(pytester: Pytester) -> None: