fix: fix mlflow test cases

[s0nicboOm]

Signed-off-by: s0nicboOm i.kushalbatra@gmail.com

1. Fix: mlflow test cases for numalogic 0.3 release
2. Fix: Flake8 file.
3. Add mlflow-skinny and mlflow to the extras dependency.
4. Add: multistage docker file.

TODO [@ab93 ]

1. Use Updated DockerImage in the pipeline example.
2. Update the toml and poetry file.
3. Update starter docs.

[s0nicboOm]

Have tested out the sample pipeline too with the new code and version. Will introduce it in another PR.