Issue #23527: Update Gmail port number for STARTTLS to 587.

Patch by Alex Shkop.
diff --git a/Lib/test/test_smtpnet.py b/Lib/test/test_smtpnet.py
index 03bf93b..15654f2 100644
--- a/Lib/test/test_smtpnet.py
+++ b/Lib/test/test_smtpnet.py
@@ -21,7 +21,7 @@
 
 class SmtpTest(unittest.TestCase):
     testServer = 'smtp.gmail.com'
-    remotePort = 25
+    remotePort = 587
 
     def test_connect_starttls(self):
         support.get_attribute(smtplib, 'SMTP_SSL')