upgrade docusaurus dependency

Note the following does not update to the latest beta docusaurus
  $ yarn upgrade docusaurus docusaurus-plugin-internaldocs-fb --latest
Therefore manually set "2.0.0-beta.15" package.json and rerun `yarn upgrade`

The docusaurus.config.js change is required in the new version due to:
facebook/docusaurus#5832

The website/src/components/GithubLink.jsx change is required due to:
facebook/docusaurus#6516

website/docusaurus.config.js

@@ -26,9 +26,6 @@ module.exports = {
         },
     },    
     themeConfig: {
-        googleAnalytics: {
-            trackingID: 'UA-149862507-1',
-        },
         algolia: {
             apiKey: '8e04f3376c4e6e060f9d8d56734fa67b',
             indexName: 'hydra',
@@ -123,6 +120,9 @@ module.exports = {
                     showLastUpdateTime: true,
                     editUrl: 'https://github.com/facebookresearch/hydra/edit/main/website/',
                 },
+                googleAnalytics: {
+                    trackingID: 'UA-149862507-1',
+                },
                 theme: {
                     customCss: require.resolve('./src/css/custom.css'),
                 },

website/package.json

@@ -10,10 +10,10 @@
     "deploy": "docusaurus deploy"
   },
   "dependencies": {
-    "@docusaurus/core": "^2.0.0-beta.14",
-    "@docusaurus/preset-classic": "^2.0.0-beta.14",
+    "@docusaurus/core": "^2.0.0-beta.15",
+    "@docusaurus/preset-classic": "^2.0.0-beta.15",
     "classnames": "^2.2.6",
-    "docusaurus-plugin-internaldocs-fb": "0.10.4",
+    "docusaurus-plugin-internaldocs-fb": "0.10.6",
     "is-svg": "4.3.1",
     "node-fetch": "^2.6.7",
     "prism-react-renderer": "1.2.1",

website/src/components/GithubLink.jsx

@@ -6,7 +6,7 @@ import React from "react";
 import Link from "@docusaurus/Link";
 import useDocusaurusContext from "@docusaurus/useDocusaurusContext";
 
-import {useActiveVersion} from "@theme/hooks/useDocs";
+import {useActiveVersion} from "@docusaurus/plugin-content-docs/client";
 
 function createGitHubUrl(to) {
     const activeVersion = useActiveVersion();