test: save the proptest seed for the grid union face that does not mesh (#1813)

Thanks @Ian-cmd-ops.

crates/kernel/tests/boolean_props.proptest-regressions

@@ -5,4 +5,5 @@
 # It is recommended to check this file in to source control so that
 # everyone who runs the test benefits from these saved cases.
 cc 739d5cbd9e471e0ff65bc2b7c1b9a323c2e769939c73def2e74fb17b0536c1d0 # shrinks to a = [0.0, 2.5, 30.0], sa = [22.5, 5.0, 5.0], b = [22.5, 7.5, 15.0], sb = [5.0, 5.0, 17.5]
+cc 0f8ee4d4597db6bdec2ad2cc7e5cfe7d4ebba351e24642118135da34bf489d0c # shrinks to a = Sph { at: [20.0, 10.0, 27.5], r: 3.75 }, b = Box { at: [15.0, 0.0, 22.5], size: [7.5, 20.0, 5.0] }
 cc 2adfe5ac6b6916fa22a415348bdd7ece29ad33e8114b94dea86ba8bc39156dee # shrinks to a = Box { at: [15.0, 22.5, 0.0], size: [5.0, 5.0, 17.5] }, b = Box { at: [2.5, 12.5, 0.0], size: [12.5, 10.0, 5.0] }