Fix NumPy 2.0 compatibility: replace deprecated .ptp() method calls with np.ptp()

[Copilot]

The match_transport.md lecture was failing with NumPy 2.0 due to the removal of the .ptp() method from ndarray objects. The error occurred when calling example_off_diag.plot_H_z():

AttributeError: `ptp` was removed from the ndarray class in NumPy 2.0. Use np.ptp(arr, ...) instead.

This PR replaces all instances of the deprecated .ptp() method with the NumPy 2.0 compatible np.ptp() function calls in the match_transport lecture:

• self.support_z.ptp() → np.ptp(self.support_z) (6 instances)
• self.X_types.ptp() → np.ptp(self.X_types) (4 instances)
• H_z.ptp() → np.ptp(H_z) (2 instances)

The changes are minimal and surgical - only method calls are replaced with function calls, preserving all existing functionality while ensuring compatibility with NumPy ≥ 2.0.

Testing: Verified with NumPy 2.3.2 that the previously failing example_off_diag.plot_H_z() call now executes successfully without errors.

Fixes #225.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[netlify]

✅ Deploy Preview for lustrous-melomakarona-3ee73e ready!

Name	Link
🔨 Latest commit	6ac4eff
🔍 Latest deploy log	https://app.netlify.com/projects/lustrous-melomakarona-3ee73e/deploys/6892b715cd8b8300089be8f0
😎 Deploy Preview	https://deploy-preview-229--lustrous-melomakarona-3ee73e.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[github-actions]

🚀 Deployed on https://6892bb36f61d0bb351a5ecce--lustrous-melomakarona-3ee73e.netlify.app

[mmcky]

@copilot did a great job here. Thanks.

This has already been manual fixed in #215 but will use this as a good example of how to use copilot