Fixes duplicate QGIS entries in Ubuntu launcher

jgrocha · nyalldawson · commit 3ce9aff5682d · 2018-12-11T12:46:57.000+10:00
(cherry picked from commit 7f4123b)
diff --git a/linux/org.qgis.qgis.desktop.in b/linux/org.qgis.qgis.desktop.in
@@ -10,3 +10,4 @@ StartupNotify=false
 Categories=Qt;Education;Science;Geography;
 MimeType=application/x-qgis-project;application/x-qgis-layer-settings;application/x-qgis-layer-definition;application/x-qgis-composer-template;image/tiff;image/jpeg;image/jp2;application/x-raster-aig;application/x-raster-ecw;application/x-raster-mrsid;application/x-mapinfo-mif;application/x-esri-shape;
 Keywords=map;globe;postgis;wms;wfs;ogc;osgeo;
+StartupWMClass=QGIS3
