chore(deps): update dependency serilog.sinks.observable to v3

Author: renovate[bot]

Directory.Packages.props

@@ -44,7 +44,7 @@
     <PackageVersion Include="Verify.SourceGenerators" Version="2.2.0" />
     <PackageVersion Include="NSubstitute" Version="5.1.0" />
     <PackageVersion Include="Serilog.Extensions.Logging" Version="8.0.0" />
-    <PackageVersion Include="Serilog.Sinks.Observable" Version="2.0.2" />
+    <PackageVersion Include="Serilog.Sinks.Observable" Version="3.0.0" />
     <PackageVersion Include="Serilog.Sinks.XUnit" Version="3.0.5" />
     <PackageVersion Include="XunitXml.TestLogger" Version="3.1.20" />
     <PackageVersion Include="coverlet.collector" Version="6.0.2" />