We need direct test dependencies only.

--- jinja2-3.1.5/tox.ini.orig
+++ jinja2-3.1.5/tox.ini
@@ -12,7 +12,7 @@
 wheel_build_env = .pkg
 constrain_package_deps = true
 use_frozen_constraints = true
-deps = -r requirements/tests.txt
+deps = -r requirements/tests.in
 commands = pytest -v --tb=short --basetemp={envtmpdir} {posargs}
 
 [testenv:py37,py3.7]