fix(backend): Remove @types/node-fetch

[woxtu]

What

@types/node-fetchを消して pnpm install するときに出る警告を解決します。

Why

Since 3.x types are bundled with node-fetch, so you don't need to install any additional packages. https://github.com/node-fetch/node-fetch?tab=readme-ov-file#typescript

Additional info (optional)

Checklist

• [x] Read the contribution guide
• [ ] Test working in a local environment
• [ ] (If needed) Add story of storybook
• [ ] (If needed) Update CHANGELOG.md
• [ ] (If possible) Add tests

[github-actions[bot]]

このPRによるapi.jsonの差分

差分はこちら

```diff ```

Get diff files from Workflow Page

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 64.90%. Comparing base (43cccaa) to head (ff9fef4).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #13948 +/- ## ============================================ - Coverage 77.84% 64.90% -12.95% ============================================ Files 185 987 +802 Lines 25595 112658 +87063 Branches 487 4484 +3997 ============================================ + Hits 19924 73116 +53192 - Misses 5664 39511 +33847 - Partials 7 31 +24 ```

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[syuilo]

🙏🏻