[Review] Add gpu tests for string functions

[ayushdg]

Adds gpu tests for string functions in dask-sql

[ayushdg]

I'm guessing this is a one off network error, but curious if you've seen this before @charlesbluca :

Error: Codecov: Failed to properly upload: The process '/home/runner/work/_actions/codecov/codecov-action/v2/dist/codecov' failed with exit code 255

[charlesbluca]

I haven't seen that issue before - do you mind rerunning tests here?

[charlesbluca]

Seems to have been a one-off 🙂

[codecov-commenter]

Codecov Report

Merging #256 (d66c1fc) into main (5d8bb74) will increase coverage by 0.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #256      +/-   ##
==========================================
+ Coverage   95.74%   95.82%   +0.07%     
==========================================
  Files          64       64              
  Lines        2750     2800      +50     
  Branches      412      424      +12     
==========================================
+ Hits         2633     2683      +50     
  Misses         75       75              
  Partials       42       42              

Impacted Files	Coverage Δ
dask_sql/cmd.py	100.00% <0.00%> (ø)
dask_sql/datacontainer.py	94.11% <0.00%> (+0.07%)	⬆️

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[ayushdg]

Should be good for another round of reviews, cc: @quasiben @galipremsagar

[galipremsagar]

@charlesbluca Could you have a look at it before we merge this? Looks like your review comments are addressed.

[charlesbluca]

LGTM, thanks @ayushdg!