♻️💄 simplify KorAPConnection class instantiations to modern syntax

Update all class instantiations from `new("KorAPConnection")` to `KorAPConnection()`.
This is possible with R >= 4.0.

Change-Id: I01131fb32045e084cafbb9e05cd8ba99f8f20f1b
diff --git a/demo/conditionsOverTime.R b/demo/conditionsOverTime.R
index ccd5592..4b96e3d 100644
--- a/demo/conditionsOverTime.R
+++ b/demo/conditionsOverTime.R
@@ -7,7 +7,7 @@
 library(RKorAPClient)
 library(ggplot2)
 
-conditionsOverTime <- function(query, conditions, years, kco = new("KorAPConnection", verbose = TRUE)) {
+conditionsOverTime <- function(query, conditions, years, kco = KorAPConnection(verbose = TRUE)) {
   g <- expand_grid(condition = conditions, year = years) %>%
     cbind(frequencyQuery(kco, query, sprintf("%s & pubDate in %d", .$condition, .$year))) %>%
     ipm() %>%