Fix Brotli test to work with updated requests

Newer versions of `requests` depend on an updated version of `urllib3`
which transparently decodes Brotli just as it does for gzip.

References #225

requirements.test.txt

@@ -1,2 +1,6 @@
+certifi==2019.9.11
+chardet==3.0.4
 coverage==4.2
-requests==2.11.1
+idna==2.8
+requests==2.22.0
+urllib3==1.25.3

tests/test_django_whitenoise.py

@@ -17,8 +17,6 @@
 from django.core.management import call_command
 from django.utils.functional import empty
 
-import brotli
-
 from whitenoise.middleware import WhiteNoiseMiddleware
 
 from .utils import TestServer, Files
@@ -91,7 +89,7 @@ def test_get_gzip(self):
     def test_get_brotli(self):
         url = storage.staticfiles_storage.url(self.static_files.js_path)
         response = self.server.get(url, headers={'Accept-Encoding': 'gzip, br'})
-        self.assertEqual(brotli.decompress(response.content), self.static_files.js_content)
+        self.assertEqual(response.content, self.static_files.js_content)
         self.assertEqual(response.headers['Content-Encoding'], 'br')
         self.assertEqual(response.headers['Vary'], 'Accept-Encoding')