chore: add gh-pages deployment to release ritual

Author: gyoshev

package.json

@@ -13,6 +13,7 @@
   },
   "license": "Apache-2.0",
   "devDependencies": {
+    "@qiwi/semantic-release-gh-pages-plugin": "^5.2.2",
     "@semantic-release/exec": "^6.0.3",
     "@types/bootstrap": "^4.5.0",
     "@types/jest": "^25.2.1",
@@ -89,7 +90,8 @@
         }
       ],
       "@semantic-release/npm",
-      "@semantic-release/github"
+      "@semantic-release/github",
+      "@qiwi/semantic-release-gh-pages-plugin"
     ]
   },
   "homepage": "https://github.com/Leanplum/Leanplum-JavaScript-SDK#readme"