style: Fix the format issue of GeometryType enumeration definition

Author: skywalker_cn

Diff for: include/openmc/constants.h

@@ -349,7 +349,7 @@ enum class RandomRaySampleMethod { PRNG, HALTON };
 //==============================================================================
 // Geometry Constants
 
-enum class GeometryType { CSG, DAG , CLS};
+enum class GeometryType { CSG, DAG, CLS };
 
 // a surface token cannot be zero due to the unsigned nature of zero for integer
 // representations. This value represents no surface.