chatview: remove excess spacing between chat contents and footer

Gitlab: #1172
Change-Id: I615caf484ab37b4a783eadc751642eeb7a5553ac

src/app/mainview/components/ChatView.qml

@@ -241,6 +241,7 @@ Rectangle {
                 SplitView.maximumWidth: root.width
                 SplitView.minimumWidth: JamiTheme.mainViewPaneMinWidth
                 SplitView.fillWidth: true
+                spacing: 0
 
                 StackLayout {
                     id: chatViewStack