Bump the python-jsonschema version used for the sanity check.

The test in this PR (#664) actually trips a bug in the older version
(where it doesn't properly consider the keys in definitions to not be
schemas, they're just labels)

bin/jsonschema_suite

@@ -498,6 +498,13 @@ class SanityTests(unittest.TestCase):
                 "title",
                 "type",
                 "uniqueItems",
+
+                # Technically this is wrong, $comment doesn't exist in this
+                # draft, but the point of this test is to detect mistakes by,
+                # test authors, whereas the point of the $comment keyword is
+                # to just standardize a place for a comment, so it's not a
+                # mistake to use it in earlier drafts in tests per se.
+                "$comment",
             },
             "draft3": {
                 "$ref",
@@ -528,6 +535,13 @@ class SanityTests(unittest.TestCase):
                 "title",
                 "type",
                 "uniqueItems",
+
+                # Technically this is wrong, $comment doesn't exist in this
+                # draft, but the point of this test is to detect mistakes by,
+                # test authors, whereas the point of the $comment keyword is
+                # to just standardize a place for a comment, so it's not a
+                # mistake to use it in earlier drafts in tests per se.
+                "$comment",
             },
         }
 

tox.ini

@@ -5,5 +5,5 @@ skipsdist = True
 
 [testenv:sanity]
 # used just for validating the structure of the test case files themselves
-deps = jsonschema==4.17.3
+deps = jsonschema==4.18.0a4
 commands = {envpython} bin/jsonschema_suite check