Refs #22258 -- Fixed an unclosed temporary file in fixtures test.

This prevented the temporary directory from being removed
on Windows.

tests/fixtures/tests.py

@@ -9,6 +9,7 @@ import warnings
 from django.apps import apps
 from django.contrib.sites.models import Site
 from django.core import management
+from django.core.files.temp import NamedTemporaryFile
 from django.core.serializers.base import ProgressBar
 from django.db import IntegrityError, connection
 from django.test import (
@@ -295,12 +296,12 @@ class FixtureLoadingTests(DumpDataAssertMixin, TestCase):
         management.call_command('loaddata', 'fixture1.json', verbosity=0)
         new_io = six.StringIO()
         new_io.isatty = lambda: True
-        _, filename = tempfile.mkstemp()
+        with NamedTemporaryFile() as file:
             options = {
                 'format': 'json',
                 'stdout': new_io,
                 'stderr': new_io,
-            'output': filename,
+                'output': file.name,
             }
             management.call_command('dumpdata', 'fixtures', **options)
             self.assertTrue(new_io.getvalue().endswith('[' + '.' * ProgressBar.progress_width + ']\n'))