chore: Fix new clippy lint

[aborgna-q]

error: unit tests in doctest are not executed
  --> src/proptest.rs:94:9
   |
94 | ///     #[test]
   |         ^^^^^^^
   |

This is just a usage example, so the block can be ignored for doctests

[codspeed-hq]

CodSpeed Performance Report

Merging this PR will improve performance by 28.6%

_{Comparing ab/fix-lint (4b692af) with main (cee8060)}

Summary

⚡ 2 improved benchmarks
✅ 49 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	clone_line_graph[10000]	772 µs	654.1 µs	+18.02%
⚡	check_convexity_sparse_LineConvexChecker<PortGraph>[1000]	7.5 µs	5.8 µs	+28.6%

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.38%. Comparing base (cee8060) to head (4b692af).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #276   +/-   ##
=======================================
  Coverage   83.38%   83.38%           
=======================================
  Files          28       28           
  Lines        7390     7390           
  Branches     7390     7390           
=======================================
  Hits         6162     6162           
  Misses       1134     1134           
  Partials       94       94           

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