22.03.2021 Migrating to go modules

The official go dependency management, go modules was just introduced slightly after grank.io was officialy launched back in 2019. Since then, as the recent go survey also confirmed, go modules has been widely adopted. Go modules became the base unit of golang dependencies and each module contains an explicit list of its dependencies, the go.mod file. This makes easier computing the dependecy graph, as no source code analysis needed anymore. Finnaly this long planned change was implemented and ranking was recomputed on the historical data. With this new approach ranks can be slightly different than they were previously.