CompatHelper: bump compat for EarthSciMLBase to 0.18 for package docs, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the EarthSciMLBase package from 0.16 to 0.16, 0.18 for package docs.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[github-actions]

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