message: remove DPC++ ifdef for solver test
  the tests are disabled from CMake's side anyways
diff: @@ -599,8 +599,6 @@ using SolverTypes =
  TYPED_TEST_SUITE(Solver, SolverTypes, TypenameNameGenerator);
  -// The tolerances we set above don't provide any useful information for float
  -#if !(GINKGO_DPCPP_SINGLE_MODE)
  TYPED_TEST(Solver, ApplyIsEquivalentToRef)
  {
  this->forall_matrix_scenarios([&](auto mtx) {
  @@ -673,4 +671,3 @@ TYPED_TEST(Solver, MixedAdvancedApplyIsEquivalentToRef)
  });
  });
  }
  -#endif
  