Pull Requests:
* https://github.com/aibasel/downward/pull/159 -- merged
* https://github.com/aibasel/downward/pull/162 -- merged

Related issues:
* issue1076

We merged the second pull request and the GitHub actions all run successfully now, 
including LP-solver tests. I'm closing this issue.

After merging the initial pull request, we noticed that the Ubuntu test cases 
were not working as intended. This was caused by changes to the CMake file that 
were necessary to fix the Windows build. In particular we discovered that the 
Ubuntu builds used to link against the static library of CPLEX even though the 
dynamic library was explicitly carried over from the compilation to the testing 
step of the workflow. The CMake changes then made the Ubuntu builds find the 
dynamic libraries instead, which caused the testing step to fail because the 
workflow did not copy over the dynamic library correctly.

We fix this issue in a new pull request 
(https://github.com/aibasel/downward/pull/162), which is ready to be merged from 
our (Florian and I) side. After merging this issue can be closed.

Once OSI is replaced by our homegrown interface (issue1076), the GitHub actions 
will have to be adapted accordingly.

On top of removing everything related to OSI, we also plan to make the actions 
use newer versions of CPLEX (22.11) and SoPlex.

In order to make SoPlex work with our new interface, we have to use a version 
that includes a pull request by Salomé which has been merged into their main 
branch, but is not yet included in a SoPlex release. On the bright side, SoPlex 
is open source as of their most recent release, which means that we no longer 
need to fetch SoPlex through a GitHub secret and can instead directly fetch from 
their GitHub repository.