add exceptions for existence_check

[Nytelife26]

This relates to...

A comment on #1174

Rationale

Prior to this, there was no way to make exceptions for regexes passed
to existence_check. The only option was to use negative lookbehinds
or lookaheads, which are both performance expensive and do not work
very well for multiple exceptions.

Changes

• An exceptions argument was added to tools.existence_check

Features

• Regex exceptions can now be made for tools.existence_check

Bug Fixes

N/A.

Breaking Changes and Deprecations

N/A.

[codecov]

Codecov Report

Merging #1182 (c21dfba) into main (8b632ef) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1182      +/-   ##
==========================================
+ Coverage   90.13%   90.14%   +0.01%     
==========================================
  Files          83       83              
  Lines        1206     1208       +2     
==========================================
+ Hits         1087     1089       +2     
  Misses        119      119              

Flag	Coverage Δ
macos-latest	90.14% <100.00%> (+0.01%)	⬆️
py3.6	89.18% <100.00%> (+0.01%)	⬆️
py3.7	89.18% <100.00%> (+0.01%)	⬆️
py3.8	90.14% <100.00%> (+0.01%)	⬆️
py3.9	90.14% <100.00%> (+0.01%)	⬆️
pypypy3	89.18% <100.00%> (+0.01%)	⬆️
ubuntu-latest	90.14% <100.00%> (+0.01%)	⬆️
windows-latest	90.14% <100.00%> (+0.01%)	⬆️

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

Impacted Files	Coverage Δ
proselint/tools.py	77.61% <100.00%> (+0.16%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8b632ef...c21dfba. Read the comment docs.