Protect against decoding errors with subprocess text mode

All these are calling subprocess in 'text mode', where it will
try to decode stdout/stderr using the default encoding (utf-8
for us). If it doesn't decode, subprocess will raise an exception
and kobo doesn't handle it, it just passes it along to us, so
things blow up - see https://pagure.io/releng/issue/12474 . To
avoid this, let's set `errors="replace"`, which tells the decoder
to replace invalid data with ? characters. This way we should get
as much of the output as can be read, and no crashes.

We also replace `universal_newlines=True` with `text=True` as
the latter is shorter, clearer, and what Python 3 subprocess
wants us to use, it considers `universal_newlines` to just be
a backwards-compatibility thing - "The universal_newlines argument
is equivalent to text and is provided for backwards compatibility"

Signed-off-by: Adam Williamson <awilliam@redhat.com>
Merges: https://pagure.io/pungi/pull-request/1812

tests/test_patch_iso.py

@@ -34,7 +34,7 @@ class TestSh(unittest.TestCase):
         patch_iso.sh(log, ["ls"], foo="bar")
         self.assertEqual(
             mock_run.call_args_list,
-            [mock.call(["ls"], foo="bar", universal_newlines=True)],
+            [mock.call(["ls"], foo="bar", text=True, errors="replace")],
         )
         self.assertEqual(log.info.call_args_list, [mock.call("Running: %s", "ls")])
         self.assertEqual(log.debug.call_args_list, [mock.call("%s", "ok")])