chore(deps): bump MQTTnet from 3.1.2 to 4.3.7.1207

Bumps [MQTTnet](https://github.com/dotnet/MQTTnet) from 3.1.2 to 4.3.7.1207.
- [Release notes](https://github.com/dotnet/MQTTnet/releases)
- [Commits](dotnet/MQTTnet@v3.1.2...v4.3.7.1207)

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

Signed-off-by: dependabot[bot] <support@github.com>

Directory.Packages.props

@@ -50,7 +50,7 @@
     <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.1" />
     <PackageVersion Include="Microsoft.Extensions.TimeProvider.Testing" Version="8.8.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.11.0" />
-    <PackageVersion Include="MQTTnet" Version="3.1.2" />
+    <PackageVersion Include="MQTTnet" Version="4.3.7.1207" />
     <PackageVersion Include="MySqlConnector" Version="2.3.7" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageVersion Include="NJsonSchema" Version="10.9.0" />