Update 4.14 changelog

Update 4.14 changelog to mention MongoDB 4.0 is no longer supported

Author: aclark4life

doc/changelog.rst

@@ -6,6 +6,7 @@ Changes in Version 4.14.0 (2025/08/06)
 
 PyMongo 4.14 brings a number of changes including:
 
+- Dropped support for MongoDB 4.0.
 - Added preliminary support for Python 3.14 and 3.14 with free-threading. We do
   not yet support the following with Python 3.14:
 
@@ -23,7 +24,6 @@ PyMongo 4.14 brings a number of changes including:
   :meth:`pymongo.mongo_client.MongoClient.append_metadata` to allow instantiated
   MongoClients to send client metadata on-demand
 - Improved performance of selecting a server with the Primary selector.
-
 - Introduces a minor breaking change. When encoding
   :class:`bson.binary.BinaryVector`, a ``ValueError`` will be raised if the
   'padding' metadata field is < 0 or > 7, or non-zero for any type other than