Describe the workflow you want to enable

Currently, there exists a lower_bound_ attribute in the fit_predict method of BaseMixture. However, the entire sequence of lower bounds is not accessible, which makes a convergence analysis more difficult to a user.

Describe your proposed solution

In addition to the lower_bound_ attribute, create a new attribute called lower_bounds_, which is a list of floats where each float is a lower bound set in

Describe alternatives you've considered, if relevant

No response

Additional context

Creating the list and appending to it would increase memory costs (but not by much). Is this a possible concern?