fix: `extract_hugr` not removing root node ports #1121

Job	Run time
Check for changes in Rust files	3s
tests (Rust stable, all features)	1m 13s
Build benchmarks 🏋️	4m 55s
check	54s
tests (Rust 1.75)	1m 54s
tests (Rust beta)	2m 6s
tests (Rust nightly)	1m 10s
tests (Rust stable, no features)	1m 23s
Required checks 🦀	1s
coverage	1m 50s
	15m 29s

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