Fix the wet/dry test for SWE

[patrickersing]

The goal of this PR is to fix the failing tests for the elixir_shallowwater_well_balanced_wet_dry.jl.

This test was observed to fail for CI runs on Intel Xeon Platinum CPUs. The L_inf error in this test seems to be highly sensitive to the specific CPU used in the run. In a sample of CI runs the following errors have been observed:

• Intel Xeon Platinum: ~8.3339e-14
• Intel Xeon E: ~1.2044e-13
• AMD EPYC: ~1.2155e-13

As the differences are negligible and seem to depend only on the specific CPU, this PR adjusts the absolute tolerance of this test from atol=500*eps() to atol=1000*eps() such that the test passes on the Intel Xeon Platinum CPUs.

[github-actions]

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[sloede]

LGTM!

[sloede]

@patrickersing format check fails :-)

[patrickersing]

@sloede I should probably add this automatic check from the style guide. It seems like the "Apply formatter"-commit is becoming part of my workflow 😄
Thanks for the review!

[andrewwinters5000]

LGTM!

[ranocha]

Thanks!