chore: update for modern python versions (>=3.9)

[kapilt]

changes for py3 support

• s/unicode/str

• s/map/list(map

• s/iterkeys/itervalues/iteritems -> keys(), values(), items()

• s/print/print()

• remove use_2to3 option which is no longer valid

❯ pip install glue
Collecting glue                                                                                                                                                                            
  Using cached glue-0.13.tar.gz (295 kB) 
  Preparing metadata (setup.py) ... error                                                                                                                                                  
  error: subprocess-exited-with-error                                                                                                                                                      
                                                                                             
  × python setup.py egg_info did not run successfully.                                       
  │ exit code: 1
  ╰─> [1 lines of output]
      error in glue setup command: use_2to3 is invalid.                                                                                                                                    
      [end of output]                                                                        
                                                                                             
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed