Fix `versionchanged` tags for json.load
`versionchanged` tags about 2.7 are useless in 3.x branches.
diff --git a/Doc/library/json.rst b/Doc/library/json.rst
index b20709f..2bdc577 100644
--- a/Doc/library/json.rst
+++ b/Doc/library/json.rst
@@ -213,7 +213,7 @@
This can be used to raise an exception if invalid JSON numbers
are encountered.
- .. versionchanged:: 2.7
+ .. versionchanged:: 3.1
*parse_constant* doesn't get called on 'null', 'true', 'false' anymore.
To use a custom :class:`JSONDecoder` subclass, specify it with the ``cls``