Explicitly outline TestRegistry destructor into .cpp file

This fixes compilation issue with C++23 mode against libstdc++.

Closes #2852

Author: horenmar

src/catch2/internal/catch_test_case_registry_impl.cpp

@@ -123,6 +123,8 @@ namespace Catch {
         return getRegistryHub().getTestCaseRegistry().getAllTestsSorted( config );
     }
 
+    TestRegistry::~TestRegistry() = default;
+
     void TestRegistry::registerTest(Detail::unique_ptr<TestCaseInfo> testInfo, Detail::unique_ptr<ITestInvoker> testInvoker) {
         m_handles.emplace_back(testInfo.get(), testInvoker.get());
         m_viewed_test_infos.push_back(testInfo.get());

src/catch2/internal/catch_test_case_registry_impl.hpp

@@ -36,6 +36,8 @@ namespace Catch {
         std::vector<TestCaseHandle> const& getAllTests() const override;
         std::vector<TestCaseHandle> const& getAllTestsSorted( IConfig const& config ) const override;
 
+        ~TestRegistry() override; // = default
+
     private:
         std::vector<Detail::unique_ptr<TestCaseInfo>> m_owned_test_infos;
         // Keeps a materialized vector for `getAllInfos`.