dependabot: ignore `groot`
Created by: c-dilks
We recently discovered that groot
version numbers are out of order. https://github.com/JeffersonLab/coatjava/pull/218 was actually a regression by several versions; therefore we revert by https://github.com/JeffersonLab/coatjava/pull/261.
This PR tells dependebot to ignore groot
to prevent this from happening again; updates to groot
will henceforth be manual.