Draft: Add support for NX, XX, GT and LT to expire and pexpire

[ghost]

Fixes #730

@WisdomPill

• Added support for nx, xx, gt and lt to django_redis/client/default.py and django_redis/client/sharded.py
• Add tests to tests/test_backend.py

Questions/TODOs [PR marked as draft]:

• Update changelog
• Should these flags be supported for expire_at and pexpire_at?
• A comment on Add option flags nx, xx, gt, lt for expire and pexpire #733 asks to add typing to expire and pexpire functions in django_redis/client/sharded.py. While I can go ahead and add it, the current implementation does not have typing in the function already, is this deliberate?

[codecov]

Codecov Report

Attention: Patch coverage is 29.66102% with 83 lines in your changes missing coverage. Please review.

Project coverage is 37.9%. Comparing base (6321750) to head (3e1d117).
Report is 11 commits behind head on master.

Files with missing lines	Patch %	Lines
tests/test_backend.py	35.6%	49 Missing ⚠️
django_redis/client/sharded.py	0.0%	32 Missing ⚠️
django_redis/client/default.py	80.0%	0 Missing and 2 partials ⚠️

❗ There is a different number of reports uploaded between BASE (6321750) and HEAD (3e1d117). Click for more details.

HEAD has 14 uploads less than BASE

Flag	BASE (6321750)	HEAD (3e1d117)
tests	14	0

Additional details and impacted files

@@            Coverage Diff            @@
##           master    #762      +/-   ##
=========================================
- Coverage    63.2%   37.9%   -25.2%     
=========================================
  Files          43      43              
  Lines        3231    3293      +62     
  Branches      244     244              
=========================================
- Hits         2039    1247     -792     
- Misses       1175    1802     +627     
- Partials       17     244     +227     

Flag	Coverage Δ
mypy	37.9% <29.7%> (-<0.1%)	⬇️
tests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[WisdomPill]

approximation needs a higher value for expire and even bigger for pexpire

[WisdomPill]

you need to add a higher tolerance have a look at the docs