Fix warning in Post costructor

In file included from /home/shubhamarora/Projects/kde/tokodon/src/abstractaccount.h:7,
                 from /home/shubhamarora/Projects/kde/tokodon/src/account.h:23,
                 from /home/shubhamarora/Projects/kde/tokodon/src/post.cpp:12:
/home/shubhamarora/Projects/kde/tokodon/src/post.h: In constructor ‘Post::Post(AbstractAccount*, QJsonObject, QObject*)’:
/home/shubhamarora/Projects/kde/tokodon/src/post.h:337:16: warning: ‘Post::m_visibility’ will be initialized after [-Wreorder]
  337 |     Visibility m_visibility;
      |                ^~~~~~~~~~~~
/home/shubhamarora/Projects/kde/tokodon/src/post.h:333:34: warning:   ‘QQmlListProperty<Attachment> Post::m_attachmentList’ [-Wreorder]
  333 |     QQmlListProperty<Attachment> m_attachmentList;
      |                                  ^~~~~~~~~~~~~~~~
/home/shubhamarora/Projects/kde/tokodon/src/post.cpp:121:1: warning:   when initialized here [-Wreorder]
  121 | Post::Post(AbstractAccount *account, QJsonObject obj, QObject *parent)
      | ^~~~