Update react-day-picker to version 9.6.7 and add date-fns dependencies (#27)

Bumped in `github/workbench-template` in
github/workbench-sdk#237.

Resolves us having to run `npm install` with a `-f` force flag. Would
also need to be run out on `github/spark-template`.

Author: gnfisher

package-lock.json

@@ -59,7 +59,7 @@
         "next-themes": "^0.4.6",
         "octokit": "^4.1.2",
         "react": "^19.0.0",
-        "react-day-picker": "^8.10.1",
+        "react-day-picker": "^9.6.7",
         "react-dom": "^19.0.0",
         "react-hook-form": "^7.54.2",
         "react-resizable-panels": "^2.1.7",