refactor: drop some conditional compile

since Qt 5.7 at least

Author: CoelacanthusHex

makespec/BUILDVERSION

@@ -1 +1 @@
-93
+94

src/exttestcasemodifier.cpp

@@ -399,11 +399,7 @@ void ExtTestCaseModifier::appendNewSub() {
 }
 
 void ExtTestCaseModifier::appendNewCase() {
-#if QT_VERSION < QT_VERSION_CHECK(5, 6, 0)
-	int who = ui->testCaseTable->getSelectedHaveSub().back();
-#else
 	int who = ui->testCaseTable->getSelectedHaveSub().constLast();
-#endif
 
 	auto *dialog = new ExtTestCaseUpdaterDialog(this, editTask, editSettings, who + 1, NO_EDIT, 1, NO_EDIT,
 	                                            NO_EDIT, NO_EDIT);

src/main.cpp

@@ -20,11 +20,9 @@
 #define LEMON_MODULE_NAME "Main"
 
 int main(int argc, char *argv[]) {
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 6, 0))
 #ifndef LEMON_QT6
 	QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling); // High DPI supported
 	QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps, true);
-#endif
 #endif
 
 	LemonBaseApplication app(argc, argv);