[style guide] Update latex `pmatrix` to `bmatrix` across all known lecture series

[mmcky]

Tracking Issue: Standardize LaTeX Matrix Notation Across Lecture Repositories

This tracks the progress of updating matrix notation from pmatrix to bmatrix across all QuantEcon lecture repositories to align with the style guide.

Progress Checklist:

• lecture-python.myst (completed in PR Standardize LaTeX math notation: replace pmatrix with bmatrix across all lecture files lecture-python.myst#526)
• lecture-julia.notebooks
• lecture-python-programming.notebooks
• lecture-datascience.notebooks
• lecture-julia.myst
• lecture-python
• lecture-datascience.myst
• lecture-python-programming.myst
• lecture-python-advanced
• lecture-python-advanced.myst
• lecture-python-advanced.notebooks
• lecture-python-programming
• lecture-python-intro
• lecture-python-intro.notebooks
• lecture-jax
• lecture-econometrics-machine-learning
• lecture-intro.zh-cn
• lecture-python.notebooks
• lecture-python.zh-cn
• lecture-jax.notebooks

Reference: QuantEcon Style Guide - Math Notation