fix: wrong initialization in DimeNet output block

[ATheCoder]

Fixes: #7762

[codecov]

Codecov Report

Merging #7774 (4a23ed5) into master (a90949d) will increase coverage by 0.04%.
The diff coverage is 100.00%.

❗ Current head 4a23ed5 differs from pull request most recent head 9e9ccc0. Consider uploading reports for the commit 9e9ccc0 to get more accurate results

@@            Coverage Diff             @@
##           master    #7774      +/-   ##
==========================================
+ Coverage   91.56%   91.61%   +0.04%     
==========================================
  Files         452      452              
  Lines       25547    25526      -21     
==========================================
- Hits        23392    23385       -7     
+ Misses       2155     2141      -14     

Impacted Files	Coverage Δ
...h_geometric/contrib/explain/graphmask_explainer.py	90.34% <100.00%> (+4.27%)	⬆️
torch_geometric/nn/models/dimenet.py	99.67% <100.00%> (ø)

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