♻️💄 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/writtenVsSpoken.R b/demo/writtenVsSpoken.R
index 87b93b4..31391ff 100644
--- a/demo/writtenVsSpoken.R
+++ b/demo/writtenVsSpoken.R
@@ -2,7 +2,7 @@
 # install_github("KorAP/RKorAPClient")
 library(RKorAPClient)
 library(ggplot2)
-g <- new("KorAPConnection", verbose=TRUE) %>%
+g <- KorAPConnection(verbose=TRUE) %>%
   frequencyQuery("sozusagen/i", vc=c("corpusSigle=FOLK", "corpusSigle!=FOLK")) %>%
   ipm() %>%
   mutate(corpus=c("FOLK", "DeReKo")) %>%