Use snitch.hpp in install test to catch missing exported headers

Author: cschreib

tests/install_tests/standalone.cpp

@@ -2,8 +2,7 @@
 #    define SNITCH_IMPLEMENTATION
 #    include <snitch/snitch_all.hpp>
 #else
-#    include <snitch/snitch_macros_check.hpp>
-#    include <snitch/snitch_macros_test_case.hpp>
+#    include <snitch/snitch.hpp>
 #endif
 
 TEST_CASE("compiles and runs") {