Fixed memory leak in test cases

tests/TreeStringTests.cpp

@@ -10,6 +10,7 @@ TEST_CASE( "Bad Statement To String", "[BoundTreeString]" ) {
     auto s = new BoundBadStatement();
     s->GetTreeString(stream, 1);
     REQUIRE(stream.str() == "\tBadStatement");
+    delete s;
 }
 
 TEST_CASE( "Break Statement To String", "[BoundTreeString]" ) {
@@ -17,6 +18,7 @@ TEST_CASE( "Break Statement To String", "[BoundTreeString]" ) {
     auto s = new BoundBreakStatement();
     s->GetTreeString(stream, 1);
     REQUIRE(stream.str() == "\tBreakStatement");
+    delete s;
 }
 
 TEST_CASE( "Block Statement To String", "[BoundTreeString]" ) {
@@ -24,6 +26,7 @@ TEST_CASE( "Block Statement To String", "[BoundTreeString]" ) {
     auto s = new BoundBlockStatement({new BoundBreakStatement(), new BoundBreakStatement()});
     s->GetTreeString(stream, 1);
     REQUIRE(stream.str() == "\tBlockStatement\n\t\tBreakStatement\n\t\tBreakStatement");
+    delete s;
 }
 
 #endif