[Dependabot]: Bump System.Text.Json in /src/NetSparkle.UI.Avalonia
[Dependabot]: Bump System.Text.Json in /src/NetSparkle.UI.Avalonia

Bumps [System.Text.Json](https://github.com/dotnet/corefx) from 4.7.1 to 4.7.2.
- [Release notes](https://github.com/dotnet/corefx/releases)
- [Commits](https://github.com/dotnet/corefx/commits)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
Deadpikle/NetSparkle,Deadpikle/NetSparkle