Look for subschemas in definitions, even in newer dialects.

Even though `definitions` was renamed to `$defs`, the JSON Schema
specifications still use SHOULD language when describing preserving
behavior for `definitions`.

Specifically they say:

    implementations SHOULD assume that "$defs" and "definitions" have
    the same behavior when that meta-schema is used.

from https://json-schema.org/draft/2020-12/json-schema-validation#name-keywords-moved-from-validat

Closes: #129

docs/changes.rst

@@ -2,6 +2,12 @@
 Changelog
 =========
 
+v0.34.0
+-------
+
+* Also look inside ``definitions`` keywords even on newer dialects.
+  The specification recommends doing so regardless of the rename to ``$defs``.
+
 v0.33.0
 -------
 

referencing/jsonschema.py

@@ -377,6 +377,7 @@ def maybe_in_subresource(
         in_subarray={"allOf", "anyOf", "oneOf", "prefixItems"},
         in_subvalues={
             "$defs",
+            "definitions",
             "dependentSchemas",
             "patternProperties",
             "properties",
@@ -400,6 +401,7 @@ def maybe_in_subresource(
         in_subarray={"allOf", "anyOf", "oneOf", "prefixItems"},
         in_subvalues={
             "$defs",
+            "definitions",
             "dependentSchemas",
             "patternProperties",
             "properties",
@@ -427,6 +429,7 @@ def maybe_in_subresource(
         in_subarray={"allOf", "anyOf", "oneOf"},
         in_subvalues={
             "$defs",
+            "definitions",
             "dependentSchemas",
             "patternProperties",
             "properties",
@@ -450,6 +453,7 @@ def maybe_in_subresource(
         in_subarray={"allOf", "anyOf", "oneOf"},
         in_subvalues={
             "$defs",
+            "definitions",
             "dependentSchemas",
             "patternProperties",
             "properties",