Tests: Replace deprecated "np.random.seed()" with "np.random.Generator()" (NPY002 warning by ruff)

[yvonnefroehlich]

Description of proposed changes

This PR aims to update the tests to follow ruff's NumPy rules, especially it addresses the NPY002 warning (please see https://docs.astral.sh/ruff/rules/numpy-legacy-random/):

NPY002 Replace legacy `np.random.seed` call with `np.random.Generator`

Example:

import numpy as np
np.random.seed(42)
np.random.normal()

is replaced by

rng = np.random.default_rng(seed=42)
rng.normal()

Affected tests

• test_io.py
• test_x2sys_cross (two times)

Please not the generated random numbers are not identical.

Related to the PRs

• Enable ruff's NumPy-specific rules #2782
• Examples: Replace deprecated "np.random.seed()" with "np.random.Generator()" (NPY002 warning by ruff) #2781

Fixes #2779 partly

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]

The changes make sense to me, but ping the original author @weiji14 to review.

[seisman]

Ping @weiji14

[weiji14]

Should be ok 🙂