[A11Y] Masquer les icônes des lecteurs d'écran (#689)

assets/sass/_theme/blocks/title.sass

@@ -21,7 +21,6 @@
         @include icon(arrow-down-s-line, before)
             font-size: pxToRem(25)
             order: 2
-            speak: none
         // When collapse is closed
         &[aria-expanded="false"]
             &::after

assets/sass/_theme/utils/icons.sass

@@ -14,7 +14,7 @@
 
 @mixin icon($icon-name: '', $pseudo-element: before, $non-breaking: false)
     &::#{$pseudo-element}
-        content: map-get($icons, $icon-name)
+        content: map-get($icons, $icon-name) #{/ ""} // Add ‘ / ""‘ to hide from screen reader
         font-family: 'Icon'
         font-style: normal
         font-variant: normal