[svd_intro.md] Update np.random → Generator API

[Chihiro2000GitHub]

Summary

This PR migrates legacy NumPy random API usage in svd_intro.md as part of QuantEcon/meta#299.

The two np.random.rand(...) calls are replaced with calls on an explicit generator rng = np.random.default_rng(), defined once in the lecture's import cell.

Related PRs and issues

I checked for open PRs and issues related to this lecture. No open PR modifies svd_intro.md, and no open issue concerns this migration.

Details

• rng = np.random.default_rng() added to the import cell.
• np.random.rand(5, 2) → rng.random((5, 2)) and np.random.rand(2, 5) → rng.random((2, 5)), in the two cells that build a random matrix X for the full-versus-reduced SVD comparison.
• No fixed seed was introduced, since the lecture did not seed before.
• No prose changes were needed: the text does not refer to np.random, and the discussion is about the shapes of U, S and V rather than the realized entries of X.
• The lecture contains no Numba (@jit, @njit, @jitclass, parallel=True, prange) code.
• A full local build completed successfully and svd_intro.md executed without errors.

Hi @mmcky and @HumphreyYang, I'd be grateful if you could take a look when you have time.

[github-actions]

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Commit: ace44f0

📚 Changed Lectures

• phillips_adaptive
• phillips_credibility
• phillips_drifts_volatilities
• phillips_escaping_nash
• phillips_learning
• phillips_lost_conquest
• phillips_misspecified
• phillips_priors
• phillips_self_confirming
• phillips_two_stories
• svd_intro

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Build Info

• Workflow: Build Project [using jupyter-book]