[extensions-web] tests: use response-provided charset instead of 'utf-8'

[Yuri Konotopov <ykonotopov src gnome org>]

commit e0816ec81d56019fec3a51daa3c695d89f9075da
Author: Yuri Konotopov <ykonotopov gnome org>
Date:   Fri Jan 11 19:28:10 2019 +0400

    tests: use response-provided charset instead of 'utf-8'

 sweettooth/extensions/tests.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/sweettooth/extensions/tests.py b/sweettooth/extensions/tests.py
index 5f98bf6..d086790 100644
--- a/sweettooth/extensions/tests.py
+++ b/sweettooth/extensions/tests.py
@@ -470,7 +470,7 @@ class UpdateVersionTest(TestCase):
         response = self.client.get(reverse('extensions-shell-update'),
                                    dict(installed=json.dumps(installed), shell_version='3.2.0'))
 
-        return json.loads(response.content.decode('utf-8'))
+        return json.loads(response.content.decode(response.charset))
 
     def test_upgrade_me(self):
         uuid = self.upgrade_uuid
@@ -537,7 +537,7 @@ class UpdateVersionTest(TestCase):
 class QueryExtensionsTest(BasicUserTestCase, TestCase):
     def get_response(self, params):
         response = self.client.get(reverse('extensions-query'), params)
-        return json.loads(response.content.decode('utf-8'))
+        return json.loads(response.content.decode(response.charset))
 
     def gather_uuids(self, params):
         if 'sort' not in params: