CLN: read_sql date parsing

[mroeschke]

• closes Inconsistent parsing for timestamp with timezone with read_sql_query #15119
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff

Cleaning up the date parsing portion of the read_sql functionality. Also checking that #15119 can be closed as we are already testing the solution.

[codecov]

Codecov Report

Merging #24500 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24500   +/-   ##
=======================================
  Coverage    92.3%    92.3%           
=======================================
  Files         166      166           
  Lines       52412    52412           
=======================================
  Hits        48381    48381           
  Misses       4031     4031

Flag	Coverage Δ
#multiple	90.73% <ø> (ø)	⬆️
#single	43.05% <ø> (-0.01%)	⬇️

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[codecov]

Codecov Report

Merging #24500 into master will decrease coverage by 60.41%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master   #24500       +/-   ##
===========================================
- Coverage    92.3%   31.88%   -60.42%     
===========================================
  Files         166      166               
  Lines       52412    52421        +9     
===========================================
- Hits        48381    16717    -31664     
- Misses       4031    35704    +31673

Flag	Coverage Δ
#multiple	30.29% <ø> (-60.44%)	⬇️
#single	31.88% <ø> (-11.17%)	⬇️

Impacted Files	Coverage Δ
pandas/io/formats/latex.py	0% <0%> (-100%)	⬇️
pandas/core/categorical.py	0% <0%> (-100%)	⬇️
pandas/io/sas/sas_constants.py	0% <0%> (-100%)	⬇️
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pandas/tseries/converter.py	0% <0%> (-100%)	⬇️
pandas/io/formats/html.py	0% <0%> (-98.65%)	⬇️
pandas/core/groupby/categorical.py	0% <0%> (-95.46%)	⬇️
pandas/core/reshape/reshape.py	8.06% <0%> (-91.51%)	⬇️
pandas/io/sas/sas7bdat.py	0% <0%> (-91.17%)	⬇️
pandas/io/sas/sas_xport.py	0% <0%> (-90.15%)	⬇️
... and 126 more

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[jreback]

looks fine. is there any user api change here? (meaning do we need a whatsnew note)

[mroeschke]

No API change at all, just reorganization. The linked issue already had an existing test, but the test wasn't as strict as it should have been.

[jreback]

thanks!