Test HANConv with empty tensors

[rusty1s]

No description provided.

[codecov]

Codecov Report

Merging #4756 (c6eda63) into master (ef78db3) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4756   +/-   ##
=======================================
  Coverage   82.47%   82.47%           
=======================================
  Files         324      324           
  Lines       17301    17301           
=======================================
  Hits        14269    14269           
  Misses       3032     3032           

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

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