Allow for multiple write types.

[koaning]

I noticed a job fail with this traceback:

Traceback (most recent call last):                                                                                      
  File "/home/vincent/Development/gh-dashb/scripts/grab_workflows.py", line 71, in <module>                             
    typer.run(scrape_workflows)                                                                                         
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/typer/main.py", line 859, in run            
    app()                                                                                                               
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/typer/main.py", line 214, in __call__       
    return get_command(self)(*args, **kwargs)                                                                           
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/click/core.py", line 829, in __call__       
    return self.main(*args, **kwargs)                                                                                   
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/click/core.py", line 782, in main           
    rv = self.invoke(ctx)                                                                                               
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/click/core.py", line 1066, in invoke        
    return ctx.invoke(self.callback, **ctx.params)                                                                      
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/click/core.py", line 610, in invoke         
    return callback(*args, **kwargs)                                                                                    
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/typer/main.py", line 497, in wrapper        
    return callback(**use_params)  # type: ignore                                                                       
  File "/home/vincent/Development/gh-dashb/scripts/grab_workflows.py", line 66, in scrape_workflows                     
    (clump_workflows.write_jsonl(output_path))                                                                          
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/clumper/clump.py", line 446, in write_jsonl 
    with open(path, "x") as f:                                                                                          
FileExistsError: [Errno 17] File exists:                                                                                
'/home/vincent/Development/gh-dashb/workflows/rasahq/rasa/workflows-2021-02-25.jsonl'   

It would be nice to allow for an overwrite flag instead of assuming "x" with the file-open here.