Fixed broken links to PyYAML page.

docs/howto/initial-data.txt

@@ -30,7 +30,7 @@ Or, you can write fixtures by hand; fixtures can be written as JSON, XML or YAML
 </topics/serialization>` has more details about each of these supported
 :ref:`serialization formats <serialization-formats>`.
 
-.. _PyYAML: https://www.pyyaml.org/
+.. _PyYAML: https://pyyaml.org/
 
 As an example, though, here's what a fixture for a simple ``Person`` model might
 look like in JSON:

docs/topics/serialization.txt

@@ -165,7 +165,7 @@ Identifier  Information
 ==========  ==============================================================
 
 .. _json: https://json.org/
-.. _PyYAML: https://www.pyyaml.org/
+.. _PyYAML: https://pyyaml.org/
 
 XML
 ---

tests/timezones/tests.py

@@ -607,7 +607,7 @@ class SerializationTests(SimpleTestCase):
     # - JSON supports only milliseconds, microseconds will be truncated.
     # - PyYAML dumps the UTC offset correctly for timezone-aware datetimes,
     #   but when it loads this representation, it subtracts the offset and
-    #   returns a naive datetime object in UTC (https://pyyaml.org/ticket/202).
+    #   returns a naive datetime object in UTC. See ticket #18867.
     # Tests are adapted to take these quirks into account.
 
     def assert_python_contains_datetime(self, objects, dt):