Show test execution times in pytest (#835)

Show the slowest tests with executation times > 0.2 s.

Reference: https://docs.pytest.org/en/stable/usage.html#profiling-test-execution-duration

Author: seisman

pyproject.toml

@@ -3,7 +3,7 @@ omit = ["*/tests/*", "*pygmt/__init__.py"]
 
 [tool.pytest.ini_options]
 minversion = "6.0"
-addopts = "--verbose --doctest-modules --mpl --mpl-results-path=results"
+addopts = "--verbose --durations=0 --durations-min=0.2 --doctest-modules --mpl --mpl-results-path=results"
 
 [tool.isort]
 profile = "black"