Fixed SSR tests (#26)

Author: Xzya

inertia/tests/test_ssr.py

@@ -1,3 +1,4 @@
+import json
 from inertia.test import InertiaTestCase, inertia_page, inertia_div
 from django.test import override_settings
 from unittest.mock import patch, Mock
@@ -24,7 +25,8 @@ def test_it_returns_ssr_calls(self, mock_request):
 
     mock_request.post.assert_called_once_with(
       'ssr-url/render',
-      json=inertia_page('props', props={'name': 'Brandon', 'sport': 'Hockey'}),
+      data=json.dumps(inertia_page('props', props={'name': 'Brandon', 'sport': 'Hockey'})),
+      headers={'Content-Type': 'application/json'},
     )
     self.assertTemplateUsed('inertia_ssr.html')
     print(response.content)