Description of proposed changes

See #2524 for context.

The failure is caused by an upstream bug, which was already fixed in GenericMappingTools/gmt#7557.

In this PR, I renamed the old test_meca_dict_eventname test to test_meca_eventname, and add a new test following #2524. The new test passes in the "GMT Tests Dev" workflow (https://github.com/GenericMappingTools/pygmt/actions/runs/5346800096) and is skipped in the "Tests" workflow (because it crashes with GMT 6.4)

Fixes #2524

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