[REVIEW] Remove warnings in test_timedelta.py

[galipremsagar]

Partially addresses #10363, by removing all warnings from test_timedelta.py.

[codecov]

Codecov Report

Merging #10418 (4dad344) into branch-22.04 (b613394) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@               Coverage Diff                @@
##           branch-22.04   #10418      +/-   ##
================================================
+ Coverage         86.13%   86.16%   +0.02%     
================================================
  Files               139      139              
  Lines             22460    22457       -3     
================================================
+ Hits              19347    19351       +4     
+ Misses             3113     3106       -7     

Impacted Files	Coverage Δ
python/cudf/cudf/io/parquet.py	92.70% <ø> (ø)
python/cudf/cudf/core/column/column.py	89.16% <100.00%> (+0.17%)	⬆️
python/cudf/cudf/core/dataframe.py	93.57% <100.00%> (ø)
python/cudf/cudf/core/frame.py	91.72% <100.00%> (ø)
python/cudf/cudf/core/single_column_frame.py	97.01% <100.00%> (ø)
python/cudf/cudf/core/column/string.py	88.39% <0.00%> (+0.12%)	⬆️
python/cudf/cudf/core/tools/datetimes.py	84.49% <0.00%> (+0.30%)	⬆️
python/cudf/cudf/core/groupby/groupby.py	91.92% <0.00%> (+0.43%)	⬆️
python/cudf/cudf/core/column/lists.py	90.56% <0.00%> (+0.47%)	⬆️

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[bdice]

@gpucibot merge