Test against jinja2 3.x (#8014)

New installs of the 2.x branch are currently broken due to https://github.com/pallets/jinja/issues/1585, which the maintainer of jinja apparently does not intend to fix.

setup.py

@@ -44,7 +44,7 @@ testing_extras = [
     "python-dateutil>=2.7",
     "pytz>=2014.7",
     "elasticsearch>=5.0,<6.0",
-    "Jinja2>=2.11,<3.0",
+    "Jinja2>=3.0,<4.0",
     "boto3>=1.16,<1.17",
     "freezegun>=0.3.8",
     "openpyxl>=2.6.4",