fix: remove =default from all destructors in headers

- Removed '= default' from all class destructors in headers
- Destructors now declared without =default (defined in .cpp)
- Fixes 'definition of explicitly-defaulted destructor' error across all classes

src/services/request.h

@@ -28,7 +28,7 @@ public:
 
     explicit Request(QObject *parent = nullptr);
     Request(Method method, const QUrl &url, const QByteArray &body = QByteArray());
-    ~Request() override = default;
+    ~Request() override;
 
     void setMethod(Method method);
     Method method() const;