♻️💄 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/displayKwics.R b/demo/displayKwics.R
index cab5807..edb6185 100644
--- a/demo/displayKwics.R
+++ b/demo/displayKwics.R
@@ -4,7 +4,7 @@
 
 query = 'V\u00F6ner' # "Portable packages must use only ASCII characters in their demos."
 
-new("KorAPConnection", verbose = TRUE) %>%
+KorAPConnection(verbose = TRUE) %>%
   auth() %>%
   corpusQuery(query, fields = c("textSigle", "pubDate", "corpusTitle", "snippet"),
               metadataOnly = FALSE) %>%