bpo-46604: fix function name in ssl module docstring (python#31064)

The function fetch_server_certificate is replaced by get_server_certificate in the module. I reflected the change in the module docstrings.

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

Lib/ssl.py

@@ -18,9 +18,10 @@
                           seconds past the Epoch (the time values
                           returned from time.time())
 
-  fetch_server_certificate (HOST, PORT) -- fetch the certificate provided
-                          by the server running on HOST at port PORT.  No
-                          validation of the certificate is performed.
+  get_server_certificate (addr, ssl_version, ca_certs, timeout) -- Retrieve the
+                          certificate from the server at the specified
+                          address and return it as a PEM-encoded string
+
 
 Integer constants: