- We do not use the other versions anyway
- Currently, if two versions are installed, even if one of them is 3.8,
sometimes the wrong one is found and the format feature is disabled

Not sure about the boost case, however...

This reverts commit cdd896c5, which is
required for e288f73a to work.

This reverts commit 0745c73b, which lead
to false test failures in dune-gdt.

This reverts commit ff1b19df.