Add pyupgrade to pre-commit and upgrade to future-style type annotations

[TRoboto]

What does this pull request change?

Upgrades to new type annotations style.

Status (please check what you already did):

• added some tests for the functionality
• updated the documentation
• tox passes

[codecov]

Codecov Report

Merging #89 (8b2ac19) into main (666b585) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main      #89   +/-   ##
=======================================
  Coverage   96.93%   96.94%           
=======================================
  Files          64       64           
  Lines        2281     2288    +7     
=======================================
+ Hits         2211     2218    +7     
  Misses         70       70           

Impacted Files	Coverage Δ
maha/expressions/general.py	100.00% <ø> (ø)
maha/cleaners/functions/contains_fn.py	100.00% <100.00%> (ø)
maha/cleaners/functions/keep_fn.py	100.00% <100.00%> (ø)
maha/cleaners/functions/normalize_fn.py	100.00% <100.00%> (ø)
maha/cleaners/functions/remove_fn.py	100.00% <100.00%> (ø)
maha/cleaners/functions/replace_fn.py	100.00% <100.00%> (ø)
maha/constants/arabic/compound.py	100.00% <100.00%> (ø)
maha/constants/english/compound.py	100.00% <100.00%> (ø)
maha/constants/general.py	100.00% <100.00%> (ø)
maha/constants/persian/compound.py	100.00% <100.00%> (ø)
... and 17 more

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[lgtm-com]

This pull request fixes 3 alerts when merging 608290b into 981e627 - view on LGTM.com

fixed alerts:

• 3 for Unused import

[lgtm-com]

This pull request fixes 3 alerts when merging 8b2ac19 into 666b585 - view on LGTM.com

fixed alerts:

• 3 for Unused import