Mark test_clone_command_injection xfail on Windows

This other GitCommandError on Windows is not related to
IndexFile.from_tree whose 8 related failing tests were marked
xfail in the preceding commit.

Also, test_clone_command_injection should not be confused with
test_clone_from_command_injection, which passes on all platforms.

The problem here appears to be that, on Windows, the path of the
directory GitPython is intended to clone to (when the possible
security vulnerability this test checks for is *absent*) is not
valid. Although this suggest the bug may only be in the test and
that the code under test may be working on Windows, but the test
does not establish that, for which it would need to test with a
payload clearly capable of creating a file unexpected_path points
to when run on its own. I am unsure if that is the case, given
that the "touch" command is used.

This doesn't appear to be reported as a bug, but some general
context about the current implementation of this test can be
examined in gitpython-developers#1531 where the last major change to it was done.

When the test is fixed, that will become more clear. At that time,
this commit can be reverted to remove the xfail mark.

test/test_repo.py

@@ -1365,6 +1365,11 @@ def test_do_not_strip_newline_in_stdout(self, rw_dir):
  r.git.commit(message="init")
  self.assertEqual(r.git.show("HEAD:hello.txt", strip_newline_in_stdout=False), "hello\n")
 
+ @pytest.mark.xfail(
+ os.name == "nt",
+ reason=R"fatal: could not create leading directories of '--upload-pack=touch C:\Users\ek\AppData\Local\Temp\tmpnantqizc\pwn': Invalid argument", # noqa: E501
+ raises=GitCommandError,
+ )
  @with_rw_repo("HEAD")
  def test_clone_command_injection(self, rw_repo):
  with tempfile.TemporaryDirectory() as tdir: