Update the doctest output due to changes in the default grid registration

[seisman]

Description of proposed changes

Fixes #

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If wrapping a new module, open a 'Wrap new GMT module' issue and submit reasonably-sized PRs.
• If adding new functionality, add an example to docstrings or tutorials.
• Use underscores (not hyphens) in names of Python files and directories.

Slash Commands

You can write slash commands (/command) in the first line of a comment to perform
specific operations. Supported slash commands are:

• /format: automatically format and lint the code
• /test-gmt-dev: run full tests on the latest GMT development version

[seisman]

Nine inline tests failed in the "Tests" workflow, in which five tests are caused due to the missing IPython package and four tests are caused by the change of the default grid registration from "pixel" to "gridline".

The four outdated inline tests are fixed by commit cff1657.

[yvonnefroehlich]

The values look now correct for me.