civix upgrade problem with Smarty mixin

The civix upgrade command won't run, it gives

                                                                                                                                                                                                                                                               
Incremental upgrades                                                                                                                                                                                                                                           
====================                                                                                                                                                                                                                                           
                                                                                                                                                                                                                                                               
Current civix format is v23.02.1.                                                                                                                                                                                                                              
No incremental upgrades required.                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                               
General upgrade                                                                                                                                                                                                                                                
===============                                                                                                                                                                                                                                                
                                                                                                                                                                                                                                                               
                                                                                                                                                                                                                                                               
In Mixlib.php line 147:                                                                                                                                                                                                                                        
                                                                                                                                                                                                                                                               
  Received incompatible version (expected="smarty-v2@1.0.1", actual="smarty-v2@1.0.0")                                                                                                                                                                         
                                                                                                                                                                                                                                                               

I'm not sure what that means.