Prepare 0.4 release

CITATION.cff

codemeta.json

docs/index.yaml

execution/helm/Chart.yaml

execution/run_uc.py

execution/theodolite.yaml

execution/uc-application/aggregation-deployment.yaml

execution/uc-workload-generator/workloadGenerator.yaml

...s/docker-test/uc1-flink-docker-compose/docker-compose.yml

...ocker-test/uc1-kstreams-docker-compose/docker-compose.yml

...s/docker-test/uc2-flink-docker-compose/docker-compose.yml

...ocker-test/uc2-kstreams-docker-compose/docker-compose.yml

...s/docker-test/uc3-flink-docker-compose/docker-compose.yml

...ocker-test/uc3-kstreams-docker-compose/docker-compose.yml

...s/docker-test/uc4-flink-docker-compose/docker-compose.yml

...ocker-test/uc4-kstreams-docker-compose/docker-compose.yml