bpo-35781: Changed references to deprecated 'warn' method in logging documentation in favour of 'warning' (GH-11654) (GH-11657)

(cherry picked from commit cda73a5af2ff064ca82140342b3158851d43868f)

Co-authored-by: yuji38kwmt <yuji38kwmt@yahoo.co.jp>
diff --git a/Doc/howto/logging.rst b/Doc/howto/logging.rst
index c90df43..7a68ca8 100644
--- a/Doc/howto/logging.rst
+++ b/Doc/howto/logging.rst
@@ -610,7 +610,7 @@
     # 'application' code
     logger.debug('debug message')
     logger.info('info message')
-    logger.warn('warn message')
+    logger.warning('warn message')
     logger.error('error message')
     logger.critical('critical message')
 
@@ -640,7 +640,7 @@
     # 'application' code
     logger.debug('debug message')
     logger.info('info message')
-    logger.warn('warn message')
+    logger.warning('warn message')
     logger.error('error message')
     logger.critical('critical message')