Fix import format at pandas/tests/io/arithmetic directory

[mwoss]

• partial Fix import formatting using isort #23334
• passes git diff upstream/master -u -- "*.py" | flake8 --diff

Ran isort --recursive pandas/tests/io/arithmetic and then checked imports using isort --recursive --check-only pandas/tests/io/arithmetic

[codecov]

Codecov Report

Merging #24579 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24579   +/-   ##
=======================================
  Coverage   92.33%   92.33%           
=======================================
  Files         166      166           
  Lines       52544    52544           
=======================================
  Hits        48516    48516           
  Misses       4028     4028

Flag	Coverage Δ
#multiple	90.76% <ø> (ø)	⬆️
#single	43.05% <ø> (ø)	⬆️

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[codecov]

Codecov Report

Merging #24579 into master will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #24579      +/-   ##
==========================================
+ Coverage   92.36%   92.38%   +0.02%     
==========================================
  Files         166      166              
  Lines       52497    52485      -12     
==========================================
+ Hits        48489    48490       +1     
+ Misses       4008     3995      -13

Flag	Coverage Δ
#multiple	90.81% <ø> (+0.02%)	⬆️
#single	43.04% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/indexes/accessors.py	91% <0%> (ø)	⬆️
pandas/core/indexes/timedeltas.py	90.22% <0%> (ø)	⬆️
pandas/core/arrays/period.py	98.53% <0%> (+0.01%)	⬆️
pandas/core/arrays/interval.py	93.08% <0%> (+0.04%)	⬆️
pandas/util/testing.py	88.09% <0%> (+0.09%)	⬆️
pandas/core/internals/blocks.py	94.49% <0%> (+0.7%)	⬆️

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[jreback]

need to merge master

[mwoss]

@jreback marged with master, tests are running at the moment

[mwoss]

@jreback Tests passed ;)

[jreback]

can you remove the files from setup.cfg (othewise its not testing these)

[mwoss]

I thought I've done that, my bad. I will do this in 4 hours.

[jreback]

lgtm. ping on green.

[jreback]

thanks @mwoss