Install explicit versions from GitHub if tags / releases are available

[nuest]

#32 packages GitHub packages.

This should (optinally, or even by default) also see if a specific version is tagged on GitHub and install that explicitly, e.g. devtools::install_github("Appsilon/shiny.collections", ref = "0.1.0")

See https://www.rdocumentation.org/packages/devtools/versions/1.13.2/topics/install_github

Apart from that, re-check installation procedure, consider using installGithub.r, see https://github.com/bhaskarvk/user2017.geodataviz/blob/master/docker/Dockerfile