Use workaround for MATOMO bug with users by country

Resolves
https://gitlab.ids-mannheim.de/tfnd/IDS-Nutzungsdatenreport/-/issues/14

Change-Id: I72015a50d145fd503b69523ba0f770ddd66e421f
diff --git a/NAMESPACE b/NAMESPACE
index 9148b1c..a9260f0 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -37,6 +37,7 @@
 importFrom(magrittr,"%>%")
 importFrom(stringr,str_replace)
 importFrom(stringr,str_replace_all)
+importFrom(stringr,str_split)
 importFrom(tibble,as_tibble)
 importFrom(tibble,rownames_to_column)
 importFrom(tidyr,complete)