small cleanup of code

include/internal/catch_interfaces_testcase.h

@@ -9,7 +9,6 @@
 #define TWOBLUECUBES_CATCH_INTERFACES_TESTCASE_H_INCLUDED
 
 #include <vector>
-#include <memory>
 
 namespace Catch {
 
@@ -20,8 +19,6 @@ namespace Catch {
         virtual ~ITestInvoker();
     };
 
-    using ITestCasePtr = std::shared_ptr<ITestInvoker>;
-
     class TestCase;
     struct IConfig;