chore(lint): cleanup unused variables in code (#1563)

website/src/components/header.js

@@ -22,7 +22,7 @@ class Header extends Component {
     window.removeEventListener('scroll', this.handleScroll);
   }
 
-  handleScroll = event => {
+  handleScroll = () => {
     const currentWindowPos =
       document.documentElement.scrollTop || document.body.scrollTop;
 

website/src/components/video-embed.js

@@ -6,7 +6,7 @@ class VideoEmbed extends Component {
   state = {
     toggled: false
   };
-  toggleVideo = event => {
+  toggleVideo = () => {
     this.setState({
       toggled: true
     });