chore(deps): update dependency gh-pages to v3.1.0 (open-telemetry#1227)

Co-authored-by: Mayur Kale <mayurkale@google.com>

package.json

@@ -50,7 +50,7 @@
     "eslint-config-airbnb-base": "14.2.0",
     "eslint-plugin-header": "3.0.0",
     "eslint-plugin-import": "2.21.2",
-    "gh-pages": "3.0.0",
+    "gh-pages": "3.1.0",
     "gts": "2.0.2",
     "husky": "4.2.5",
     "lerna": "3.22.1",