Extract the CDM version attribute from a cdm_reference object
Examples
if (FALSE) {
library(CDMConnector)
con <- DBI::dbConnect(duckdb::duckdb(), eunomia_dir())
cdm <- cdm_from_con(con, cdm_schema = "main", write_schema = "main")
version(cdm)
DBI::dbDisconnect(con, shutdown = TRUE)
}