is_installed helper function does not work in R4.4.x

[egillax]

This snippet here from helpers-install.R:

is_installed <- function (pkg, version = 0) {
  installed_version <- tryCatch(utils::packageVersion(pkg), 
                                error = function(e) NA)
  !is.na(installed_version) && installed_version >= version
}

Doesn't work in R>=4.4 . The comparison installed_version >= version fails because installed_version is a packageVersion object and can't be compared to a numeric anymore. The fix is to change it to:

installed_version >= as.character(version)

[egillax]

This was reported by a PLP user OHDSI/PatientLevelPrediction#493