Update tutorials to build faster

[willschlitzer]

Inadvertent creation of new branch due to changing remote git repository. This is the updated version of #868, including @seisman's comments to remove figures.

Fixes#825

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 adding new functionality, add an example to docstrings or tutorials.

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]

We may speed up the 3d perspective tutorial by using a lower-resolution earth relief grid if #873 can be merged.

[seisman]

@willschlitzer#873 is already merged. You may try to use low-resolution grids and see if the build time can be reduced.

In the Cache Data workflow, only 01d, 30m, 10m and 05m resolution earth relief grids are cached in the CI jobs. So you may try 10m grid.