fix - Ubuntu - Broken Flameshot icon in the taskbar with pinned image

(cherry picked from commit 18722f5b29dde05f22d0a88b7e2251f81a06ca00)

src/tools/pin/pinwidget.cpp

@@ -27,6 +27,7 @@ PinWidget::PinWidget(const QPixmap& pixmap, QWidget* parent)
   : QWidget(parent)
   , m_pixmap(pixmap)
 {
+    setWindowIcon(QIcon(":img/app/flameshot.svg"));
     setWindowFlags(Qt::WindowStaysOnTopHint | Qt::FramelessWindowHint);
     // set the bottom widget background transparent
     setAttribute(Qt::WA_TranslucentBackground);