Avoid package upgrades during CI
The .gitlab.ci.yml currently does all kinds of dnf install
and pip install
calls which mean that each run of the CI can have different results depending on what stuff the package managers install.
We should ensure that the Docker image used for CI contains all the dependencies that are needed. This may require having a separate tag used for running the tests, as we don't want to bloat the image that we provide for people who just want to run BuildStream too much.