♿️(controls) change play button aria-label value when its state change

The aria-label attribute set on all play buttons does not change
according the player state. When the video is playing, the aria-label
should change to pause otherwise screen reader will not detect that this
button now can be used to pause the video.

src/js/ui.js

@@ -214,6 +214,7 @@ const ui = {
         // Set state
         Array.from(this.elements.buttons.play || []).forEach(target => {
             Object.assign(target, { pressed: this.playing });
+            target.setAttribute('aria-label', i18n.get(this.playing ? 'pause' : 'play', this.config));
         });
 
         // Only update controls on non timeupdate events