Remove use of lxml (#4133)

Also marks test introduced in #4133 as flaky.

Author: jmsmkn

app/tests/documentation_tests/test_views.py

@@ -188,6 +188,7 @@ def nested_docpages():
 
 
 @pytest.mark.django_db
+@pytest.mark.flaky(reruns=3)
 @pytest.mark.parametrize(
     "level, num_queries",
     (

app/tests/groups_tests/test_views.py

@@ -1,5 +1,5 @@
 import pytest
-from lxml.html.diff import html_escape
+from django.utils.html import escape
 
 from tests.algorithms_tests.factories import AlgorithmFactory
 from tests.archives_tests.factories import ArchiveFactory
@@ -53,7 +53,7 @@ def get_user_autocomplete():
         assert response.status_code == 200
         assert str(u.pk) in response.json()["results"][0]["id"]
         assert (
-            html_escape(str(u.user_profile.get_mugshot_url()))
+            escape(str(u.user_profile.get_mugshot_url()))
             in response.json()["results"][0]["text"]
         )
         assert u.username in response.json()["results"][0]["text"]
@@ -122,7 +122,7 @@ def get_user_autocomplete():
 
         assert str(u.pk) in response.json()["results"][0]["id"]
         assert (
-            html_escape(str(u.user_profile.get_mugshot_url()))
+            escape(str(u.user_profile.get_mugshot_url()))
             in response.json()["results"][0]["text"]
         )
         assert u.username in response.json()["results"][0]["text"]