Added missing includes for libc++ and MSVC

Author: cschreib

tests/memory_tracker.hpp

@@ -1,4 +1,5 @@
 #include <cstdlib>
+#include <new>
 
 // Allocation tracker, to catch memory leaks and double delete
 constexpr std::size_t max_allocations = 20'000;

tests/runtime_tests_lifetime.cpp

@@ -2,6 +2,7 @@
 #include "testing.hpp"
 #include "tests_common.hpp"
 
+#include <algorithm>
 #include <vector>
 
 TEMPLATE_LIST_TEST_CASE("observer expiring scope", "[lifetime][owner][observer]", owner_types) {