PIPELINE: Use correct pytest command

.docker/Dockerfile

@@ -32,4 +32,4 @@ CMD /wait-for-it.sh caosdb-server:10443 -t 500 -- \
     cp /git/.docker/sss_pylinkahead.ini /scripting/home/.pylinkahead.ini && \
     cp -r /git/resources /scripting/bin-debug && \
     # ... and run tests
-    pytest --cov=linkahead -vv {posargs}
+    pytest --cov=linkahead -vv tests