[kalman_2] Refactor simulate_workers for PEP8 compliance and code clarity

[suda-yuga]

This PR refactors the simulate_workers function to follow Python best practices and enhance readability. The main changes include:

• Replaced isinstance(..., type(None)) with is None checks for clarity.
• Avoided unnecessary equality checks like diff == True in favor of direct boolean evaluation.
• Used is None instead of == None for None comparisons.
• Replaced unnecessary list unpacking like [y_hat_t[i]] = worker.G @ x_hat with scalar extraction using .item().
  The matrix multiplication returns a single-element array, so using .item() explicitly converts it to a scalar value, improving code clarity and avoiding the need for list unpacking.

[mmcky]

thank you for this PR @suda-yuga

I really like these changes.

@HumphreyYang I think using .item() method is cleaner than the unpacking [] syntax on the LHS. What do you think?

[HumphreyYang]

@HumphreyYang I think using .item() method is cleaner than the unpacking [] syntax on the LHS. What do you think?

Thanks @mmcky! I agree. I think unpacking [] is more concise but probably less transparent to readers. Thanks @suda-yuga!