Add fixer for required on_delete argument

[browniebroke]

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[codecov-commenter]

Codecov Report

Merging #61 (6580366) into main (f42bdd7) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #61   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           24        25    +1     
  Lines          765       793   +28     
  Branches       128       132    +4     
=========================================
+ Hits           765       793   +28     

Impacted Files	Coverage Δ
src/django_upgrade/fixers/on_delete.py	100.00% <100.00%> (ø)

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[adamchainz]

LGTM. One thing is we could insert the argument first, after any positional args, rather than last. This would require passing the number of positional arguments through to add_on_delete_keyword It's more informational than other field arguments.

[browniebroke]

One thing is we could insert the argument first, after any positional args, rather than last. This would require passing the number of positional arguments through to add_on_delete_keyword It's more informational than other field arguments.

That's a good point, also on_delete is the second positional argument in the implementation, so that matches up well too. I'll try to make it work...

[adamchainz]

I made a commit and it looks okay to me, so merging! Thanks!

[browniebroke]

Thanks for finishing it up 👍🏻