Bump System.IO.Ports from 6.0.0 to 7.0.0

Bumps [System.IO.Ports](https://github.com/dotnet/runtime) from 6.0.0 to 7.0.0.
- [Release notes](https://github.com/dotnet/runtime/releases)
- [Commits](dotnet/runtime@v6.0.0...v7.0.0)

---
updated-dependencies:
- dependency-name: System.IO.Ports
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

SerialPortRx/SerialPortRx.csproj

@@ -2,7 +2,7 @@
 
   <ItemGroup>
     <PackageReference Include="System.Reactive" Version="5.0.0" />
-    <PackageReference Include="System.IO.Ports" Version="6.0.0" />
+    <PackageReference Include="System.IO.Ports" Version="7.0.0" />
   </ItemGroup>
 
   <ItemGroup>