Update dependency gh-pages to v6

packages/webapp/public/98.css/package.json

@@ -30,11 +30,11 @@
     "cssnano": "^5.0.1",
     "dedent": "^0.7.0",
     "ejs": "^3.0.2",
-    "gh-pages": "^2.2.0",
+    "gh-pages": "^6.0.0",
     "glob": "^7.1.6",
     "highlight.js": "^10.4.1",
     "live-server": "^1.2.1",
-    "mkdirp": "^3.0.0",
+    "mkdirp": "^1.0.4",
     "postcss": "^8.2.12",
     "postcss-calc": "^7.0.2",
     "postcss-copy": "^7.1.0",