Fix the sanity check by pinning.
Currently using latest tickles a bug in my own implementation unfortunately.
@@ -5,5 +5,5 @@ skipsdist = True
[testenv:sanity]
# used just for validating the structure of the test case files themselves
-deps = jsonschema>=3.2.0
+deps = jsonschema==3.2.0
commands = {envpython} bin/jsonschema_suite check
