Remove last usages of deprecated logging.warn method (#6314)

changelog.d/6314.misc

@@ -0,0 +1 @@
+Replace every instance of `logger.warn` method with `logger.warning` as the former is deprecated.

synapse/config/logger.py

@@ -234,8 +234,8 @@ def setup_logging(
 
     # make sure that the first thing we log is a thing we can grep backwards
     # for
-    logging.warn("***** STARTING SERVER *****")
-    logging.warn("Server %s version %s", sys.argv[0], get_version_string(synapse))
+    logging.warning("***** STARTING SERVER *****")
+    logging.warning("Server %s version %s", sys.argv[0], get_version_string(synapse))
     logging.info("Server hostname: %s", config.server_name)
 
     return logger

synapse/handlers/directory.py

@@ -250,7 +250,7 @@ class DirectoryHandler(BaseHandler):
                     ignore_backoff=True,
                 )
             except CodeMessageException as e:
-                logging.warn("Error retrieving alias")
+                logging.warning("Error retrieving alias")
                 if e.code == 404:
                     result = None
                 else: