chore(deps): update actions/cache action to v3 (#12)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/cache](https://togithub.com/actions/cache) | action | major | `v2` -> `v3` |

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### Release Notes

<details>
<summary>actions/cache</summary>

### [`v3`](https://togithub.com/actions/cache/compare/v2...v3)

[Compare Source](https://togithub.com/actions/cache/compare/v2...v3)

</details>

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### Configuration

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♻ **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.

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.github/workflows/documentation.yml

@@ -10,7 +10,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - name: Cache gems
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: vendor/bundle
           key: ${{ runner.os }}-flow-${{ hashFiles('**/Gemfile.lock') }}