GATConv: make use of edge_updater

[rusty1s]

No description provided.

[codecov]

Codecov Report

Merging #4342 (fe5c1bc) into master (70333f9) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #4342      +/-   ##
==========================================
- Coverage   82.30%   82.30%   -0.01%     
==========================================
  Files         310      310              
  Lines       15894    15891       -3     
==========================================
- Hits        13082    13079       -3     
  Misses       2812     2812              

Impacted Files	Coverage Δ
torch_geometric/nn/conv/gat_conv.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 70333f9...fe5c1bc. Read the comment docs.