Test flake in `f64::symmetric_eigen`

https://github.com/dimforge/nalgebra/actions/runs/7680821854/job/21547472692?pr=1357
```rust
failures:

---- linalg::eigen::proptest_tests::f64::symmetric_eigen stdout ----
proptest: Saving this and future failures in /home/runner/work/nalgebra/nalgebra/proptest-regressions/linalg/eigen.txt
proptest: If this test was run on a CI system, you may wish to add the following line to your copy of the file. (You may need to create it.)
cc 22215195c9a500add7e9df74a70f843da62923c7085bab4d70c9562979d21f02
thread 'linalg::eigen::proptest_tests::f64::symmetric_eigen' panicked at tests/linalg/eigen.rs:71:5:
Test failed: assertion failed: relative_eq!(m.lower_triangle(), recomp.lower_triangle(), epsilon = 1.0e-5) at tests/linalg/eigen.rs:71.
minimal failing input: n = 14
successes: 1
local rejects: 0
global rejects: 0

failures:
linalg::eigen::proptest_tests::f64::symmetric_eigen
```