Add test cases for TripleStore

[alkidbaci]

Should add test cases for TripleStore related classes because it would be harder to find the issue once it is reported later on.
Since triplestore kb requires an endpoint, it would be nice if we can host a knowledge base somewhere where it would always be available.

[Demirrr]

Yes indeed

[Demirrr]

We should intergate the following steps into github actions to test TripleStore

Using jena-fuseki

1. sudo docker run -p 3030:3030 -e ADMIN_PASSWORD=pw123 stain/jena-fuseki
2. Login http://localhost:3030/#/ with admin and pw123
3. Create a new dataset and upload the RDF Triple