[libcalamaresui] LocaleLabel doesn't need to inherit QObject

- Use static QObject::tr instead.

src/libcalamaresui/utils/CalamaresUtilsGui.cpp

@@ -270,7 +270,7 @@ LocaleLabel::LocaleLabel( const QString& locale )
     : m_locale( LocaleLabel::getLocale( locale ) )
     , m_localeId( locale )
 {
-    QString longFormat = tr( "%1 (%2)", "Language (Country)" );
+    QString longFormat = QObject::tr( "%1 (%2)", "Language (Country)" );
 
     QString sortKey = QLocale::languageToString( m_locale.language() );
     QString languageName = m_locale.nativeLanguageName();

src/libcalamaresui/utils/CalamaresUtilsGui.h

@@ -134,10 +134,8 @@ constexpr int windowPreferredHeight = 520;
  * translation system) into QLocales, and also into consistent
  * human-readable text labels.
  */
-class LocaleLabel : public QObject
+class LocaleLabel
 {
-    Q_OBJECT
-
 public:
     /** @brief Construct from a locale name.
      *