Update renku and CI pipelines

With !51 (merged) the build should be fixed. This enables us to

• Update the Dockerfile for renku. The idea would be that users can open a session on renku and run the examples.
• Improve the CI pipelines. As there are several people contributing to the project it would be beneficial to run the test, and the linting in the CI pipeline. So we make sure that we only merge code that pass the pipeline.