(Question) Tweak/strip-out Prophet to run linear regression (or some deterministic model; or at least remove randomization)

I noticed that Prophet does not always return the exact same result, seems some randomization is happening even if mcmc is disabled. Below's the Prophet default settings:

```
m = Prophet(
growth='linear'
, changepoints=None
, n_changepoints=25
, changepoint_range=0.8
, yearly_seasonality='auto'
, weekly_seasonality='auto'
, daily_seasonality='auto'
, holidays=None
, seasonality_mode='additive'
, seasonality_prior_scale=10.0
, holidays_prior_scale=10.0
, changepoint_prior_scale=0.05
, mcmc_samples=0
, interval_width=0.8
, uncertainty_samples=1000
, stan_backend=None
)
```

I would like to tweak/strip it in order to make it perform a simple linear regression (or some other deterministic simple model) and then start adding complexity.

Any ideas?