test: Update map_layers test baseline image

[camdecoster]

Description

Update the test baseline image for the map_layers mock. This fixes a failing test.

Testing

Let CI run and see if the test-baselines steps complete successfully.

Notes

• The changes are small and only in this test
• I'm not sure what would have prompted this change, but it's been consistently failing with the same image diff
  

[emilykl]

Thanks Cam!

[emilykl]

Yeah @camdecoster as discussed, this could plausibly be a change in the map tiles (which are loaded from the web).