Install Dask nightly last in CI

[pentschev]

By installing Dask nightly as last step in CI, we prevent any other steps from inadvertently downgrading it before running tests.

[codecov-commenter]

Codecov Report

Base: 0.00% // Head: 0.00% // No change to project coverage 👍

Coverage data is based on head (0133a2e) compared to base (3e5a19b).
Patch has no changes to coverable lines.

❗ Current head 0133a2e differs from pull request most recent head 6e4c9cf. Consider uploading reports for the commit 6e4c9cf to get more accurate results

Additional details and impacted files

@@              Coverage Diff               @@
##           branch-22.12   #1029     +/-   ##
==============================================
  Coverage          0.00%   0.00%             
==============================================
  Files                25      17      -8     
  Lines              3321    2216   -1105     
==============================================
+ Misses             3321    2216   -1105     

Impacted Files	Coverage Δ
dask_cuda/_version.py
dask_cuda/benchmarks/local_cupy_map_overlap.py
dask_cuda/benchmarks/utils.py
dask_cuda/benchmarks/local_cudf_merge.py
dask_cuda/benchmarks/common.py
dask_cuda/benchmarks/local_cudf_groupby.py
dask_cuda/benchmarks/local_cupy.py
dask_cuda/benchmarks/local_cudf_shuffle.py

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[msadang]

LGTM

[pentschev]

Thanks @msadang .

[pentschev]

@gpucibot merge