chore: bump up codecov/codecov-action action to v4 (#5758)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [codecov/codecov-action](https://togithub.com/codecov/codecov-action) | action | major | `v3` -> `v4` |

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### Release Notes

<details>
<summary>codecov/codecov-action (codecov/codecov-action)</summary>

### [`v4`](https://togithub.com/codecov/codecov-action/compare/v3...v4)

[Compare Source](https://togithub.com/codecov/codecov-action/compare/v3...v4)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

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.github/workflows/build-test.yml

@@ -190,7 +190,7 @@ jobs:
         run: yarn nx test:coverage @affine/monorepo
 
       - name: Upload unit test coverage results
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           files: ./.coverage/store/lcov.info
@@ -353,7 +353,7 @@ jobs:
           DATABASE_URL: postgresql://affine:affine@localhost:5432/affine
 
       - name: Upload server test coverage results
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           files: ./packages/backend/server/.coverage/lcov.info