fix: NonConvex error on SiblingSubgraph::from_nodes with multiports #1300

Job	Run time
Check for changes in Rust files	3s
Build benchmarks 🏋️	5m 27s
tests (Rust stable, no features)	1m 15s
check	1m 8s
tests (Rust 1.75)	1m 59s
tests (Rust stable, all features)	1m 3s
tests (Rust beta)	1m 41s
tests (Rust nightly)	1m 24s
Required checks 🦀	1s
coverage	2m 28s
	16m 29s

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