DEPR: favour sep over delimiter in pd.read_csv

[minggli]

• closes Inconsistent behaviour on sep/delimiter for pandas.read_csv #21996
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

following discussion in #21996 and #7662, pandas uses sep extensively and in to_csv counterpart too. This PR deprecates delimiter argument from 0.24.0

comments welcome.

[pep8speaks]

Hello @minggli! Thanks for submitting the PR.

• There are no PEP8 issues in the file pandas/io/parsers.py !

• There are no PEP8 issues in the file pandas/tests/io/parser/common.py !

• There are no PEP8 issues in the file pandas/tests/io/parser/dialect.py !

[WillAyd]

Looks generally good. Could use a whatsnew note. Also looks like some test cases need to still be updated per CI failures

[jorisvandenbossche]

As mentioned in the issue, I think we should decide on deprecating this or not together with the discussion in #22639

[codecov]

Codecov Report

Merging #23158 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #23158      +/-   ##
==========================================
+ Coverage   92.14%   92.14%   +<.01%     
==========================================
  Files         170      170              
  Lines       50992    50993       +1     
==========================================
+ Hits        46985    46986       +1     
  Misses       4007     4007

Flag	Coverage Δ
#multiple	90.56% <100%> (ø)	⬆️
#single	42.32% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
pandas/io/parsers.py	95.6% <100%> (ø)	⬆️

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[codecov]

Codecov Report

Merging #23158 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #23158      +/-   ##
==========================================
+ Coverage   92.22%   92.22%   +<.01%     
==========================================
  Files         169      169              
  Lines       50911    50912       +1     
==========================================
+ Hits        46954    46955       +1     
  Misses       3957     3957

Flag	Coverage Δ
#multiple	90.65% <100%> (ø)	⬆️
#single	42.29% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
pandas/io/parsers.py	95.6% <100%> (ø)	⬆️

---

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 92fd46c...2d7b7ab. Read the comment docs.

[minggli]

@WillAyd actioned. but something unrelated seems to break azure CI

[jreback]

i think we are hold for now on this.

[minggli]

@jreback, cool, just ping if anything is decided or needs change! thanks 👍

[jreback]

will do @minggli

[WillAyd]

Closing as stale. If we want another PR here should continue discussion back in original issue