Use dayjs instead of moment (#92)

package.json

@@ -19,10 +19,10 @@
     "autoprefixer": "^10.4.14",
     "codemirror": "^6.0.1",
     "cssnano": "^5.1.15",
+    "dayjs": "^1.11.9",
     "github-markdown-css": "^5.2.0",
     "highlight.js": "^11.7.0",
     "markdown-it": "^13.0.1",
-    "moment": "^2.29.3",
     "nodemon": "^2.0.22",
     "postcss": "^8.4.13",
     "postcss-cssnext": "^3.1.1",