Updated NetworkX version to 2.5.1

[rlratzel]

Updated NetworkX version to latest version, which addresses an incompatibility with the latest decorator dependency.

Tested by running the BC tests which were previously failing with Nx 2.5

[codecov-io]

Codecov Report

Merging #1510 (f960676) into branch-0.19 (1f0f14e) will increase coverage by 2.07%.
The diff coverage is 45.11%.

@@               Coverage Diff               @@
##           branch-0.19    #1510      +/-   ##
===============================================
+ Coverage        58.24%   60.32%   +2.07%     
===============================================
  Files               71       70       -1     
  Lines             3281     3153     -128     
===============================================
- Hits              1911     1902       -9     
+ Misses            1370     1251     -119     

Impacted Files	Coverage Δ
python/cugraph/dask/common/input_utils.py	22.32% <12.50%> (-0.76%)	⬇️
python/cugraph/dask/centrality/katz_centrality.py	29.16% <25.00%> (-5.62%)	⬇️
python/cugraph/dask/community/louvain.py	29.03% <25.00%> (-4.31%)	⬇️
python/cugraph/dask/link_analysis/pagerank.py	21.87% <25.00%> (-3.94%)	⬇️
python/cugraph/dask/traversal/bfs.py	27.58% <25.00%> (-4.56%)	⬇️
python/cugraph/dask/traversal/sssp.py	27.58% <25.00%> (-4.56%)	⬇️
python/cugraph/structure/number_map.py	63.82% <51.42%> (+4.61%)	⬆️
python/cugraph/_version.py	44.80% <0.00%> (+0.39%)	⬆️

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[BradReesWork]

@gpucibot merge