qt6, test: Use qWarning() instead of QWARN() macro

The `QWARN()` macro internally uses `QTest::qWarn()`, which has been
deprecated since Qt 6.3. Replacing it with `qWarning()` ensures
compatibility across all Qt versions.

Author: hebasto

src/qt/test/addressbooktests.cpp

@@ -222,8 +222,8 @@ void AddressBookTests::addressBookTests()
         // framework when it tries to look up unimplemented cocoa functions,
         // and fails to handle returned nulls
         // (https://bugreports.qt.io/browse/QTBUG-49686).
-        QWARN("Skipping AddressBookTests on mac build with 'minimal' platform set due to Qt bugs. To run AppTests, invoke "
-              "with 'QT_QPA_PLATFORM=cocoa test_bitcoin-qt' on mac, or else use a linux or windows build.");
+        qWarning() << "Skipping AddressBookTests on mac build with 'minimal' platform set due to Qt bugs. To run AppTests, invoke "
+                      "with 'QT_QPA_PLATFORM=cocoa test_bitcoin-qt' on mac, or else use a linux or windows build.";
         return;
     }
 #endif

src/qt/test/apptests.cpp

@@ -60,8 +60,8 @@ void AppTests::appTests()
         // framework when it tries to look up unimplemented cocoa functions,
         // and fails to handle returned nulls
         // (https://bugreports.qt.io/browse/QTBUG-49686).
-        QWARN("Skipping AppTests on mac build with 'minimal' platform set due to Qt bugs. To run AppTests, invoke "
-              "with 'QT_QPA_PLATFORM=cocoa test_bitcoin-qt' on mac, or else use a linux or windows build.");
+        qWarning() << "Skipping AppTests on mac build with 'minimal' platform set due to Qt bugs. To run AppTests, invoke "
+                      "with 'QT_QPA_PLATFORM=cocoa test_bitcoin-qt' on mac, or else use a linux or windows build.";
         return;
     }
 #endif

src/qt/test/test_main.cpp

@@ -58,7 +58,7 @@ int main(int argc, char* argv[])
     gArgs.ForceSetArg("-natpmp", "0");
 
     std::string error;
-    if (!gArgs.ReadConfigFiles(error, true)) QWARN(error.c_str());
+    if (!gArgs.ReadConfigFiles(error, true)) qWarning() << error.c_str();
 
     // Prefer the "minimal" platform for the test instead of the normal default
     // platform ("xcb", "windows", or "cocoa") so tests can't unintentionally

src/qt/test/wallettests.cpp

@@ -475,8 +475,8 @@ void WalletTests::walletTests()
         // framework when it tries to look up unimplemented cocoa functions,
         // and fails to handle returned nulls
         // (https://bugreports.qt.io/browse/QTBUG-49686).
-        QWARN("Skipping WalletTests on mac build with 'minimal' platform set due to Qt bugs. To run AppTests, invoke "
-              "with 'QT_QPA_PLATFORM=cocoa test_bitcoin-qt' on mac, or else use a linux or windows build.");
+        qWarning() << "Skipping WalletTests on mac build with 'minimal' platform set due to Qt bugs. To run AppTests, invoke "
+                      "with 'QT_QPA_PLATFORM=cocoa test_bitcoin-qt' on mac, or else use a linux or windows build.";
         return;
     }
 #endif