Update connections.py

 authMechanisms = {'NOSASL', 'PLAIN', 'KERBEROS', 'LDAP'}    
if it wirite like above,when run it ,it will case an err,
like this:
   authMechanisms = {'NOSASL','PLAIN','KERBEROS','LDAP'}
                              ^
SyntaxError: invalid syntax


i edit like this:
     authMechanisms = ('NOSASL', 'PLAIN', 'KERBEROS', 'LDAP')
and it runs ok.