[change_ramsey] Updates to Code Required

[mmcky]

The following Deprecation and Runtime Warnings are being issued in this lecture

Code:

ch1 = ChangModel(β=0.3, mbar=30, h_min=0.99, h_max=1/0.3,
                 n_h=8, n_m=35, N_g=50)
ch2 = ChangModel(β=0.8, mbar=30, h_min=0.1, h_max=1/0.8,
                 n_h=20, n_m=50, N_g=50)

showing

 RuntimeWarning: invalid value encountered in log  uc = lambda c: np.log(c)

and

ch1.solve_bellman(θ_min=0.01, θ_max=0.0499, order=30, tol=1e-6)
ch2.solve_bellman(θ_min=0.045, θ_max=0.15, order=30, tol=1e-6)

showing

DeprecationWarning: Conversion of an array with ndim > 0 to a scalar is deprecated, and will error in future. Ensure you extract a single element from your array before performing this operation. (Deprecated NumPy 1.25.)
  p_iter1[i] = -p_fun(res.x)
RuntimeWarning: invalid value encountered in log
  uc = lambda c: np.log(c)
Convergence achieved after 15 iterations
DeprecationWarning: Conversion of an array with ndim > 0 to a scalar is deprecated, and will error in future. Ensure you extract a single element from your array before performing this operation. (Deprecated NumPy 1.25.)
  p_grid[i] = p
DeprecationWarning: Conversion of an array with ndim > 0 to a scalar is deprecated, and will error in future. Ensure you extract a single element from your array before performing this operation. (Deprecated NumPy 1.25.)
  resid_grid[i] = np.dot(cheb.chebvander(scale, order-1), c) - p
DeprecationWarning: Conversion of an array with ndim > 0 to a scalar is deprecated, and will error in future. Ensure you extract a single element from your array before performing this operation. (Deprecated NumPy 1.25.)
  θ_series[0] = res.x
RuntimeWarning: Values in x were outside bounds during a minimize step, clipping to bounds
  fx = wrapped_fun(x)
RuntimeWarning: Values in x were outside bounds during a minimize step, clipping to bounds
  g = append(wrapped_grad(x), 0.0)
RuntimeWarning: Values in x were outside bounds during a minimize step, clipping to bounds
  a_eq = vstack([con['jac'](x, *con['args'])
RuntimeWarning: Values in x were outside bounds during a minimize step, clipping to bounds
  a_ieq = vstack([con['jac'](x, *con['args'])

[mmcky]

@kp992 would you mind taking a look at this and resolving these issues?

Note; there is a file loaded in this lecture from _static/lecture_specific/change_credible