Update mockcache

[ilan-gold]

mockcache (https://github.com/lunant/mockcache), on its masterbranch, is python3 compatible but its latest release is not (lunant/mockcache#8). We either need to reach out for a new build, or call the master branch directly in order to upgrade to Python 3 (#2619). Currently it is used in the core utils as part of invalidate_cached_object.

[hackdna]

I would look into removing the caching functionality completely.

[hackdna]

It looks like mockcache package is no longer maintained: the last commit in the Github repo was made in 2016.

[iurisilvio]

I just released mockcache3 lib. It is a mockcache fork with some small enhancements. https://github.com/buserbrasil/mockcache3

[ilan-gold]

@iurisilvio thanks so much! we stopped maintaining this project a long time ago though, i appreciate the active update!