A new version of R will be released on 2019-04-26. One significant change is the support of HCL colour definitios and palettes. Some defaults for colour palettes are changing (for the better) but small differences may visible in how plots look compared to earlier R versions. There is a post with a summary at the R blog, and a paper arXiv:1903.0649 describing why better palettes for data plotting can be defined.
Another significant change is that serialization format 3 becomes the default. As this format can be read only by R (>= 3.5.0) when sharing files created with
saveRDS(), and when sharing saved workspaces one needs to make sure the recipient is using a recent version of R or override this new default to create the files to be shared using the older serialization format 2.
All the packages I maintain should work correctly under R (= 3.6.0), but if you discover a problem, please, raise an issue at bitbucket within the repository of the affected package.