chore(deps): update actions/setup-dotnet action to v6 (#22)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
|
[actions/setup-dotnet](https://redirect.github.com/actions/setup-dotnet)
| action | major | `v5` → `v6` |

---

### Release Notes

<details>
<summary>actions/setup-dotnet (actions/setup-dotnet)</summary>

###
[`v6.0.0`](https://redirect.github.com/actions/setup-dotnet/releases/tag/v6.0.0)

[Compare
Source](https://redirect.github.com/actions/setup-dotnet/compare/v6.0.0...v6.0.0)

##### What's Changed

- Migrate to ESM and upgrade dependencies by
[@&#8203;priyagupta108](https://redirect.github.com/priyagupta108) in
[#&#8203;752](https://redirect.github.com/actions/setup-dotnet/pull/752)
- Bump actions/checkout from 6.0.3 to 7.0.0 by
[@&#8203;dependabot](https://redirect.github.com/dependabot)\[bot] in
[#&#8203;751](https://redirect.github.com/actions/setup-dotnet/pull/751)
- chore(deps): bump
[@&#8203;actions/cache](https://redirect.github.com/actions/cache) to
6.2.0 by [@&#8203;philip-gai](https://redirect.github.com/philip-gai) in
[#&#8203;756](https://redirect.github.com/actions/setup-dotnet/pull/756)

##### New Contributors

- [@&#8203;philip-gai](https://redirect.github.com/philip-gai) made
their first contribution in
[#&#8203;756](https://redirect.github.com/actions/setup-dotnet/pull/756)

**Full Changelog**:
<actions/setup-dotnet@v5...v6.0.0>

###
[`v6`](https://redirect.github.com/actions/setup-dotnet/compare/v5.4.0...v6.0.0)

[Compare
Source](https://redirect.github.com/actions/setup-dotnet/compare/v5.4.0...v6.0.0)

</details>

---

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---

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---

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View the [repository job
log](https://developer.mend.io/github/Arbeidstilsynet/action-dotnet-publish).

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Author: renovate[bot]

action.yml

@@ -27,7 +27,7 @@ runs:
     # --- Trusted publishing path ---
     - name: Setup .NET SDK (trusted publishing)
       if: inputs.use-trusted-publishing == 'true'
-      uses: actions/setup-dotnet@26b0ec14cb23fa6904739307f278c14f94c95bf1 # v5
+      uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
       with:
         dotnet-version: ${{ inputs.dotnet-version }}
         config-file: ${{ inputs.config-file }}
@@ -52,7 +52,7 @@ runs:
     # --- Authenticated publishing path ---
     - name: Setup .NET SDK (authenticated)
       if: inputs.use-trusted-publishing != 'true'
-      uses: actions/setup-dotnet@26b0ec14cb23fa6904739307f278c14f94c95bf1 # v5
+      uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
       with:
         dotnet-version: ${{ inputs.dotnet-version }}
         source-url: ${{ inputs.source-url }}