Change iteritems to items()

[bbimber]

Hello,

We're getting an error with pandas 2.0.3:

2023-08-14T17:16:56.7430548Z [19] "Traceback (most recent call last):"                                                                                                                                                                                               
2023-08-14T17:16:56.7431013Z [20] "  File \"/usr/lib/python3.10/runpy.py\", line 196, in _run_module_as_main"                                                                                                                                                        
2023-08-14T17:16:56.7431467Z [21] "    return _run_code(code, main_globals, None,"                                                                                                                                                                                   
2023-08-14T17:16:56.7431928Z [22] "  File \"/usr/lib/python3.10/runpy.py\", line 86, in _run_code"                                                                                                                                                                   
2023-08-14T17:16:56.7432357Z [23] "    exec(code, run_globals)"                                                                                                                                                                                                      
2023-08-14T17:16:56.7433028Z [24] "  File \"/home/runner/.local/lib/python3.10/site-packages/demuxEM/__main__.py\", line 13, in <module>"                                                                                                                            
2023-08-14T17:16:56.7433447Z [25] "    main()"                                                                                                                                                                                                                       
2023-08-14T17:16:56.7434101Z [26] "  File \"/home/runner/.local/lib/python3.10/site-packages/demuxEM/__main__.py\", line 9, in main"                                                                                                                                 
2023-08-14T17:16:56.7434523Z [27] "    command.execute()"                                                                                                                                                                                                            
2023-08-14T17:16:56.7435348Z [28] "  File \"/home/runner/.local/lib/python3.10/site-packages/demuxEM/commands/DemuxEM.py\", line 61, in execute"                                                                                                                     
2023-08-14T17:16:56.7435773Z [29] "    run_pipeline("                                                                                                                                                                                                                
2023-08-14T17:16:56.7436450Z [30] "  File \"/home/runner/.local/lib/python3.10/site-packages/demuxEM/pipeline/pipeline.py\", line 94, in run_pipeline"                                                                                                               
2023-08-14T17:16:56.7436931Z [31] "    for name, value in rna_data.obs[\"demux_type\"].value_counts().iteritems():"                                                                                                                                                  
2023-08-14T17:16:56.7437609Z [32] "  File \"/home/runner/.local/lib/python3.10/site-packages/pandas/core/generic.py\", line 5989, in __getattr__"                                                                                                                    
2023-08-14T17:16:56.7438053Z [33] "    return object.__getattribute__(self, name)"                                                                                                                                                                                   
2023-08-14T17:16:56.7438669Z [34] "AttributeError: 'Series' object has no attribute 'iteritems'"  

This is probably due to this change in pandas:

See: pandas-dev/pandas#45321

This PR changes iteritems() or items(), as suggested.

[yihming]

Hello @bbimber . Apology for my late response. I'll go ahead merging your PR, and set the version threshold for pandas dependency as well.