Add compatibility with Psycopg 3

[hartungstenio]

This fixes the issue #190

[hartungstenio]

I'm just having to work around this test: https://github.com/Hipo/drf-extra-fields/blob/master/tests/test_fields.py#L835

Basically, psycopg 3 will adjust the bounds to () to include infinites, while psycopg 2 will keep [)

Any ideas on how to approach this.

[james-certn]

Generally looks good!

[codecov-commenter]

Codecov Report

Merging #202 (044cc82) into master (da86adf) will decrease coverage by 0.15%.
The diff coverage is 100.00%.

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@@            Coverage Diff             @@
##           master     #202      +/-   ##
==========================================
- Coverage   93.98%   93.84%   -0.15%     
==========================================
  Files           4        4              
  Lines         482      471      -11     
==========================================
- Hits          453      442      -11     
  Misses         29       29              

Impacted Files	Coverage Δ
tests/test_fields.py	96.30% <100.00%> (-0.12%)	⬇️

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[KaratasFurkan]

Thanks a lot for your contribution @hartungstenio, we are really sorry for the late reply & review. Extra thanks for organizing imports and some styling.

It looks good overall but we prefer to not create a breaking change. I made comments regarding it. It would be nice if you update the PR according to these comments. Thanks again!

[KaratasFurkan]

Great! Thanks again for this important patch.