Bump MQTTnet from 3.1.0 to 3.1.1 (#1623)

Bumps [MQTTnet](https://github.com/chkr1011/MQTTnet) from 3.1.0 to 3.1.1.
- [Release notes](https://github.com/chkr1011/MQTTnet/releases)
- [Commits](dotnet/MQTTnet@v3.1.0...v3.1.1)

---
updated-dependencies:
- dependency-name: MQTTnet
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Libraries/Opc.Ua.PubSub/Opc.Ua.PubSub.csproj

@@ -34,7 +34,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="MQTTnet" Version="3.1.0" />
+    <PackageReference Include="MQTTnet" Version="3.1.1" />
     <PackageReference Include="System.Net.NetworkInformation" Version="4.3.0" />
   </ItemGroup>