fix rolling groupby with negative windows

[ritchie46]

fixes #4002

[codecov-commenter]

Codecov Report

Merging #4010 (20c5fb3) into master (f794a07) will decrease coverage by 0.00%.
The diff coverage is 70.73%.

@@            Coverage Diff             @@
##           master    #4010      +/-   ##
==========================================
- Coverage   62.62%   62.61%   -0.01%     
==========================================
  Files         447      447              
  Lines       73971    74035      +64     
==========================================
+ Hits        46322    46358      +36     
- Misses      27649    27677      +28     

Impacted Files	Coverage Δ
polars/polars-time/src/groupby/dynamic.rs	46.11% <0.00%> (-1.87%)	⬇️
polars/polars-time/src/windows/groupby.rs	77.84% <95.08%> (+1.89%)	⬆️
...s/polars-core/src/chunked_array/ops/take/traits.rs	51.61% <0.00%> (-5.38%)	⬇️
...s/polars-core/src/series/implementations/floats.rs	59.13% <0.00%> (-0.93%)	⬇️
polars/polars-core/src/chunked_array/cast.rs	72.22% <0.00%> (-0.70%)	⬇️
polars/polars-core/src/utils/mod.rs	52.23% <0.00%> (-0.36%)	⬇️
...olars/polars-core/src/frame/groupby/into_groups.rs	55.52% <0.00%> (-0.30%)	⬇️
polars/polars-core/src/datatypes/mod.rs	49.90% <0.00%> (-0.19%)	⬇️
polars/polars-core/src/fmt.rs	44.58% <0.00%> (ø)
... and 6 more

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