exclude test that unconditionally requires sci-libs/spglib
* https://bugs.gentoo.org/765811

--- a/tests/core/CMakeLists.txt
+++ b/tests/core/CMakeLists.txt
@@ -15,7 +15,6 @@
   Molecule
   Mutex
   RingPerceiver
-  Spacegroup
   Utilities
   UnitCell
   Variant