don't traceback when server doesn't have SSL support. Fixes #7322

src/common/connection.py

@@ -1328,7 +1328,7 @@ class Connection(CommonConnection, ConnectionHandlers):
                     certificate=con.Connection.ssl_certificate[i]))
                 return True
             i += 1
-        if hasattr(con.Connection, 'ssl_fingerprint_sha1'):
+        if con.Connection.ssl_fingerprint_sha1:
             saved_fingerprint = gajim.config.get_per('accounts', self.name,
                 'ssl_fingerprint_sha1')
             if saved_fingerprint: