i3-config: Change lock shortcut

In order for the super-l key combination to be available in other
programs change it to super-shift-l.

.config/i3/config

@@ -41,7 +41,7 @@ bindsym $mod+Shift+Return exec i3-sensible-editor
 bindsym $mod+Print exec scrot ~/tmp/screenshots/'%Y-%m-%d_%H:%M:%S_$wx$h.png'
 
 # lock screen
-bindsym $mod+l exec fuzzy-i3lock
+bindsym $mod+Shift+l exec fuzzy-i3lock
 
 # kill focused window
 bindsym $mod+Shift+q kill