update functions and tests to align with RKorAPClient 0.9.0

Change-Id: I0221c6cc0b9180bc83feb96651e0a5f204846451
diff --git a/pyproject.toml b/pyproject.toml
index 9cc876d..c32b40c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "KorAPClient"
-version = "0.8.1"
+version = "0.9.0"
 description = "Client package to access KorAP's web service API"
 authors = [
     {name = "Marc Kupietz",email = "kupietz@ids-mannheim.de"},