Fix for array param

[ruslankrivoshein]

I don't know how clumsy this method is, but it helps me in the next case:

{
  "action": "edit",
  "data[1][title]": "title",
  "data[1][files][]": 1,
  "data[1][files][]": 2,
  "data[1][files][]": 3
}

Existing tests pass successfully, but it's useful to cover the fix case as well.

[codecov-io]

Codecov Report

Merging #5 into master will decrease coverage by 0.37%.
The diff coverage is 80%.

@@            Coverage Diff             @@
##           master       #5      +/-   ##
==========================================
- Coverage     100%   99.62%   -0.38%     
==========================================
  Files           4        4              
  Lines         266      270       +4     
==========================================
+ Hits          266      269       +3     
- Misses          0        1       +1

Impacted Files	Coverage Δ
rest_framework_datatables_editor/viewsets.py	98.24% <80%> (-1.76%)	⬇️

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[vertliba]

I don't know how clumsy this method is, but it helps me in the next case:

{
  "action": "edit",
  "data[1][title]": "title",
  "data[1][files][]": 1,
  "data[1][files][]": 2,
  "data[1][files][]": 3
}

Existing tests pass successfully, but it's useful to cover the fix case as well.

Hi @ruslankrivoshein!.
Thank you for your contribution!
Could you rebase the PR to the latest version and add tests for that case?