feat: upgrade gh-pages from 3.1.0 to 6.1.1

Snyk has created this PR to upgrade gh-pages from 3.1.0 to 6.1.1.

See this package in npm:
gh-pages

See this project in Snyk:
https://app.snyk.io/org/cachiman/project/3f55f266-fab6-4312-96b7-5d5335ca6056?utm_source=github-cloud-app&utm_medium=referral&page=upgrade-pr

package.json

@@ -14,7 +14,7 @@
     "babel-preset-minify": "^0.5.1",
     "browser-sync": "^2.26.13",
     "del": "^6.0.0",
-    "gh-pages": "^3.1.0",
+    "gh-pages": "^6.1.1",
     "gulp": "^4.0.2",
     "gulp-autoprefixer": "^7.0.1",
     "gulp-babel": "^8.0.0",