feat(tket2-hseries): Add `tket2.futures` Hugr extension #1496

Job	Run time
Check for changes	6s
Check Python code 🐍	36s
Check Rust code 🦀	2m 1s
Build benchmarks 🏋️	4m 16s
tests (Python)	1m 45s
tests (Rust stable, all features)	2m 18s
tests (Rust 1.75)	2m 30s
tests (Rust stable, no features)	2m 35s
tests (Rust beta)	2m 35s
tests (Rust nightly-2024-05-22)	2m 17s
Check Python coverage 🐍	1m 49s
Check Rust coverage 🦀	2m 43s
Required checks 🦀+🐍	1s
	25m 32s

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