Unexpected interaction of fmt libraries

opm-common also ships fmt as we do. There seems to be some strange interaction such that when opm-common is present our unit test fails: https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/jobs/88066. Maybe the opm-shipped library is included and there is a version mismatch of some sort.

121/545 Test #119: test_format ................................................Child aborted***Exception:   0.27 sec
terminate called after throwing an instance of 'Dune::Exception'
  what():  Dune::Exception [testString:/builds/dumux-repositories/dumux/test/io/format/test_format.cc:15]: Unexpected result: Hubble's H₀ ≅42 miles/sec/mpc., expected Hubble's H₀ ≅ 42 miles/sec/mpc.