Update Prettier for package.json

Next sometimes wants to patch `package-lock.json`. The old Prettier setting indended with 4 spaces, but Next always indends with 2 spaces. Since `npm install` automatically uses the indendation from `package.json` for `package-lock.json` and to avoid the format switching back and forth, both files are now set to 2 spaces.

website/.prettierrc

@@ -22,7 +22,7 @@
         {
             "files": ["package.json", "package-lock.json"],
             "options": {
-                "tabWidth": 4,
+                "tabWidth": 2,
                 "printWidth": 80,
                 "proseWrap": "always"
             }