Refactor some uses of virtual -> override

src/catch2/generators/catch_generators.hpp

@@ -29,7 +29,7 @@ namespace Detail {
 
     template<typename T>
     struct IGenerator : GeneratorUntypedBase {
-        virtual ~IGenerator() = default;
+        ~IGenerator() override = default;
 
         // Returns the current element of the generator
         //

src/catch2/internal/catch_test_case_registry_impl.hpp

@@ -33,7 +33,7 @@ namespace Catch {
 
     class TestRegistry : public ITestCaseRegistry {
     public:
-        virtual ~TestRegistry() = default;
+        ~TestRegistry() override = default;
 
         virtual void registerTest( std::unique_ptr<TestCaseInfo> testInfo, std::unique_ptr<ITestInvoker> testInvoker );