COMP: Fix QPixmapCache::find deprecation warnings in ctkPixmapIconEngine

This commit fixes warnings like the following reported when building
against Qt >= 5.13.

  /path/to/S-r/CTK/Libs/Widgets/ctkPixmapIconEngine.cpp:187:27: warning: 'find' is deprecated: Use bool find(const QString &, QPixmap *) instead
        [-Wdeprecated-declarations]
          if (QPixmapCache::find(key + QString::number(static_cast<int>(mode)), pm))
                            ^
  /path/to/Support/Qt/5.15.2/clang_64/lib/QtGui.framework/Headers/qpixmapcache.h:80:5: note: 'find' has been explicitly marked deprecated here
      QT_DEPRECATED_X("Use bool find(const QString &, QPixmap *) instead")
      ^
  /path/to/Support/Qt/5.15.2/clang_64/lib/QtCore.framework/Headers/qglobal.h:294:33: note: expanded from macro 'QT_DEPRECATED_X'
  #  define QT_DEPRECATED_X(text) Q_DECL_DEPRECATED_X(text)
                                  ^
  /path/to/Support/Qt/5.15.2/clang_64/lib/QtCore.framework/Headers/qcompilerdetection.h:675:55: note: expanded from macro 'Q_DECL_DEPRECATED_X'
  #    define Q_DECL_DEPRECATED_X(text) __attribute__ ((__deprecated__(text)))
                                                        ^

Libs/Widgets/ctkPixmapIconEngine.cpp

@@ -184,9 +184,9 @@ QPixmap ctkPixmapIconEngine::pixmap(const QSize &size, QIcon::Mode mode, QIcon::
 
 
     if (mode == QIcon::Active) {
-        if (QPixmapCache::find(key + QString::number(static_cast<int>(mode)), pm))
+        if (QPixmapCache::find(key + QString::number(static_cast<int>(mode)), &pm))
             return pm; // horray
-        if (QPixmapCache::find(key + QString::number(static_cast<int>(QIcon::Normal)), pm)) {
+        if (QPixmapCache::find(key + QString::number(static_cast<int>(QIcon::Normal)), &pm)) {
             QStyleOption opt(0);
             opt.palette = QApplication::palette();
             QPixmap active = QApplication::style()->generatedIconPixmap(QIcon::Active, pm, &opt);
@@ -195,7 +195,7 @@ QPixmap ctkPixmapIconEngine::pixmap(const QSize &size, QIcon::Mode mode, QIcon::
         }
     }
 
-    if (!QPixmapCache::find(key + QString::number(static_cast<int>(mode)), pm)) {
+    if (!QPixmapCache::find(key + QString::number(static_cast<int>(mode)), &pm)) {
         if (pm.size() != actualSize)
             pm = pm.scaled(actualSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
         if (pe->mode != mode && mode != QIcon::Normal) {