rm unused const

Tests/Unit/Base/SpinMatrixTest.cpp

@@ -2,8 +2,6 @@
 #include "Base/Spin/Spinor.h"
 #include "Tests/GTestWrapper/google_test.h"
 
-const double epsilon = 1e-12;
-
 const complex_t A{1., 5.};
 const complex_t B{2., 6.};
 const complex_t C{3., 7.};