Replace deprecated op parameter with predicate

[MaGering]

With this PR the Future warning

sys:1: FutureWarning: The `op` parameter is deprecated and will be removed in a future release. Please use the `predicate` parameter instead.

is removed by using the parameter predicate instead of op.

[MaGering]

Outdated: Checks not working due to problem described in my comment here. Hence this PR should be merged after #336.

Checks pass as of the state of commit 0e667a2.

[MaGering]

Ready for review @Stefanie08!

[Stefanie08]

Thank you for fixing the FutureWarning. The changes work as expected, although new FutureWarnings are raised. A new issue will follow.

[MaGering]

Thank you for fixing the FutureWarning. The changes work as expected, although new FutureWarnings are raised. A new issue will follow.

Thanks for checking @Stefanie08.

If I execute the rule which belongs to this PR

snakemake -j1 prepare_conv_pp

I do not get any further Future Warnings. Note that to test this rule, all files except oemof-B3/results/_resources/scal_costs_efficiencies.csv must be there.

If there are other FutureWarnings, you need to identify at which rule they occur. You can do this from the output in the console or the log file.
Please only create an issue in the oemof-B3 repo if it is a FutureWarning that is triggered by code used in this repo. If it is a FutureWarning triggered in demandlib for example, you would have to create an issue there. Thanks a lot!