Flaky test: TestComputeAvgVnAndGraddivVnAndVt

[havogt]

Since the tolerance is already quite relaxed, we should probably investigate if there is something off.

=========================== short test summary info ============================
FAILED tests/dycore/stencil_tests/test_compute_avg_vn_and_graddiv_vn_and_vt.py::TestComputeAvgVnAndGraddivVnAndVt::test_TestComputeAvgVnAndGraddivVnAndVt - AssertionError: 
Not equal to tolerance rtol=1e-07, atol=0
Verification failed for 'vt'
Mismatched elements: 1 / 2051270 (4.88e-05%)
Max absolute difference: 8.8817842e-16
Max relative difference: 2.91424112e-07
 x: array([[-0.316735, -0.496815, -0.362142, ...,  0.344697, -0.024296,
         0.048611],
       [-0.891145, -0.837449, -0.089364, ..., -0.662814, -0.726733,...
 y: array([[-0.316735, -0.496815, -0.362142, ...,  0.344697, -0.024296,
         0.048611],
       [-0.891145, -0.837449, -0.089364, ..., -0.662814, -0.726733,...
======= 1 failed, 81 passed, 8 skipped, 78 warnings in 730.31s (0:12:10) =======