Add video attributes to always allow iOS playback

Fixes blank (black) screen when in low power mode on iOS.
https://webkit.org/blog/6784/new-video-policies-for-ios/

Author: adriangoransson

src/components/QrcodeReader.vue

@@ -26,6 +26,9 @@
         ref="video"
         v-show="shouldScan"
         class="qrcode-reader__camera"
+        autoplay
+        muted
+        playsinline
       ></video>
     </div>
   </div>