Add weighted sampling support in `random_walk`

@rusty1s I have recently submitted a pull request for the node2vec algorithm, which implements a weighted random walk. I am eagerly anticipating the merging of this code into the main branch. 😊

Codecov Report

Merging #7858 (89242c5) into master (c0c060c) will decrease coverage by 0.11%. Report is 1 commits behind head on master. The diff coverage is 31.91%.

:exclamation: Current head 89242c5 differs from pull request most recent head 76317f9. Consider uploading reports for the commit 76317f9 to get more accurate results

@@            Coverage Diff             @@
##           master    #7858      +/-   ##
==========================================
- Coverage   89.36%   89.26%   -0.11%     
==========================================
  Files         457      457              
  Lines       26817    26855      +38     
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+ Hits        23965    23971       +6     
- Misses       2852     2884      +32     

Files Changed	Coverage Δ
torch_geometric/nn/models/node2vec.py	71.87% <31.91%> (-22.25%)	:arrow_down:

... and 6 files with indirect coverage changes

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Wondering if there is any update on this? Edge weights would be an incredible addition to Node2Vec.