fixed dependency statsmodels==0.12.2

[thepr0blem]

Is this strict dependency on specific version obligatory? It makes packaging projects with kats and other time series related dependencies problematic. Example would be darts which requires statsmodels>0.13, but in general statsmodels is a dependency for many projects and it would make deps conflicts resolution much easier.

Thanks!

[michaelbrundage]

It's a problem for sure. statsmodels keeps breaking kats with backwards incompatible changes in their minor point releases. We added kats.compat.statsmodels to compensate for some of the issues in their latest releases. The problem is that statsmodels>0.13 made many more incompatible changes that have broken more kats dependencies, and the team hasn't yet had time to investigate and fix. PRs always welcome!