Fixed memory leak in unit tests

tests/PokemonTests/ExperienceGainTests.cpp

@@ -13,5 +13,7 @@ TEST_CASE("Basic Experience gain test", "battling") {
     auto expLib = lib->GetExperienceLibrary();
     expLib->HandleExperienceGain(mon2, {mon1});
     REQUIRE(mon1->GetExperience() - initialExp == 4339);
+    delete mon1;
+    delete mon2;
 }
 #endif