Remove unnecessary #include

This will make it easier to port these tests to different contexts.
diff --git a/test/HexFloat.cpp b/test/HexFloat.cpp
index affb145..5b97f4a 100644
--- a/test/HexFloat.cpp
+++ b/test/HexFloat.cpp
@@ -20,7 +20,6 @@
 #include <tuple>
 
 #include <gmock/gmock.h>
-#include "UnitSPIRV.h"
 #include "source/util/hex_float.h"
 
 namespace {