Switches from facebookgo/clock to benbjohnson/clock

[FilWisher]

This PR switches from the facebookgo/clock dependency to benbjohnson/clock which is the more actively maintained drop-in replacement.

It also initializes the module using go mody init.

[arshamalh]

Changing to github.com/benbjohnson/clock causes tests to fail, it seems that function implementations are also different 🤔