Migrate Figure.grdcontour tests to dvc

[michaelgrund]

Description of proposed changes

Related to #1131.

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

[github-actions]

Summary of changed images

This is an auto-generated report of images that have changed on the DVC remote

Status	Path
added	pygmt/tests/baseline/test_grdcontour.png
added	pygmt/tests/baseline/test_grdcontour_file.png
added	pygmt/tests/baseline/test_grdcontour_interval_file_full_opts.png
added	pygmt/tests/baseline/test_grdcontour_labels.png
added	pygmt/tests/baseline/test_grdcontour_slice.png

Image diff(s)

• pygmt/tests/baseline/test_grdcontour.png

• pygmt/tests/baseline/test_grdcontour_file.png

• pygmt/tests/baseline/test_grdcontour_interval_file_full_opts.png

• pygmt/tests/baseline/test_grdcontour_labels.png

• pygmt/tests/baseline/test_grdcontour_slice.png

Report last updated at commit 6cef3e4

[seisman]

Quick comment: pygmt/tests/baseline/test_grdcontour.png should be removed.

[michaelgrund]

Quick comment: pygmt/tests/baseline/test_grdcontour.png should be removed.

Noticed that, will change it, thanks @seisman.

[seisman]

This test check if grdcontour works for a grid file input, so shouldn't be changed to grid.

[michaelgrund]

Thanks! Rechanged it.