Version 0.4+dfsg1-1 of r-cran-dt is marked for autoremoval from testing on Wed 21 Nov 2018. It depends (transitively) on twitter-bootstrap, affected by #907724. You should try to prevent the removal by fixing these RC bugs.
Last update: 2018-10-22
Standards version of the package is outdated.
The package should be updated to follow the last version of Debian Policy
(Standards-Version 4.2.1 instead of