Use mipmap on custom reactions

resources/qml/Reactions.qml

@@ -77,6 +77,7 @@ Flow {
                     source: modelData.key.startsWith("mxc://") ? (modelData.key.replace("mxc://", "image://MxcImage/") + "?scale") : ""
                     visible: modelData.key.startsWith("mxc://")
                     width: textMetrics.height
+                    mipmap: true
                 }
                 Rectangle {
                     id: divider