Add support for unique TextFields

[diesieben07]

Adds support for unqiue on TextField, similar to CharField.
Fixes #331.

[pep8speaks]

Hello @diesieben07! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-05-17 21:27:10 UTC

[codecov]

Codecov Report

Merging #332 (79821ff) into main (1b7f02a) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #332   +/-   ##
=======================================
  Coverage   96.32%   96.32%           
=======================================
  Files           6        6           
  Lines         272      272           
=======================================
  Hits          262      262           
  Misses         10       10           

Impacted Files	Coverage Δ
model_clone/mixins/clone.py	95.62% <100.00%> (ø)
model_clone/utils.py	96.87% <100.00%> (ø)

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[jackton1]

@all-contributors please add @diesieben07 for test, bug

[allcontributors]

@jackton1

I've put up a pull request to add @diesieben07! 🎉

[jackton1]

@all-contributors please add @diesieben07 for code

[allcontributors]

@jackton1

I've updated the pull request to add @diesieben07! 🎉