rm duplicated edges from the observed graph

[codecov[bot]]

Codecov Report

Base: 99.62% // Head: 99.59% // Decreases project coverage by -0.02% :warning:

Coverage data is based on head (51c85a0) compared to base (521f2a7). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #42 +/- ## ========================================== - Coverage 99.62% 99.59% -0.03% ========================================== Files 76 76 Lines 3709 3719 +10 ========================================== + Hits 3695 3704 +9 - Misses 14 15 +1 ``` | [Impacted Files](https://codecov.io/gh/SherylHYX/pytorch_geometric_signed_directed/pull/42?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Yixuan+He) | Coverage Δ | | |---|---|---| | [...metric\_signed\_directed/utils/general/link\_split.py](https://codecov.io/gh/SherylHYX/pytorch_geometric_signed_directed/pull/42/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Yixuan+He#diff-dG9yY2hfZ2VvbWV0cmljX3NpZ25lZF9kaXJlY3RlZC91dGlscy9nZW5lcmFsL2xpbmtfc3BsaXQucHk=) | `98.22% <100.00%> (-0.39%)` | :arrow_down: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Yixuan+He). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Yixuan+He)

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