[Test] Run 'appdelete' at end of GTest tests

This makes it easier to find memory leaks when using Valgrind by suppressing
false positives associated with data cached by Cantera.

test/kinetics/pdep.cpp

@@ -230,5 +230,7 @@ int main(int argc, char** argv)
 {
     printf("Running main() from pdep.cpp\n");
     testing::InitGoogleTest(&argc, argv);
-    return RUN_ALL_TESTS();
+    int result = RUN_ALL_TESTS();
+    Cantera::appdelete();
+    return result;
 }

test/thermo/nasapoly.cpp

@@ -148,5 +148,7 @@ int main(int argc, char** argv)
 {
     printf("Running main() from nasapoly.cpp\n");
     testing::InitGoogleTest(&argc, argv);
-    return RUN_ALL_TESTS();
+    int result = RUN_ALL_TESTS();
+    Cantera::appdelete();
+    return result;
 }