Bump Flink version to 1.20

[michaelkoepf]

Is your feature request related to a problem? Please describe.
The current Flink version is 1.17, which does not support newer features regarding elasticity, e.g., externalized declarative resource management

Describe the solution you'd like
Update to Flink 1.20.

Describe alternatives you've considered
Updating directly to Flink 2.X. However, this might need a more in-depth evaluation regarding deprecations, as it is major upgrade. Sticking with 1.20 for now should be fine.

Additional context
n/a

[SoerenHenning]

I very much like the idea of upgrading the implementations to latest framework versions to keep ShuffleBench relevant. However, I would prefer to update all frameworks to their latest releases (according to a specific date) to preserve fairness in the benchmark.

We also should create a release with the current implementation to ensure reproducibility of existing and published research.

[michaelkoepf]

Note: Flink version should be at least 1.20.1, because 1.20 has a bug in the UI that does not show the busy time.