Update dependency System.Reactive to v7

Author: dependencyupdates[bot]

src/Directory.Packages.props

@@ -90,7 +90,7 @@
     <PackageVersion Include="System.IdentityModel.Tokens.Jwt" Version="8.19.2" />
     <PackageVersion Include="System.Management" Version="$(RuntimeFrameworkVersion)" />
     <PackageVersion Include="System.Management.Automation" Version="7.6.4" />
-    <PackageVersion Include="System.Reactive" Version="6.1.0" />
+    <PackageVersion Include="System.Reactive" Version="7.0.0" />
     <PackageVersion Include="System.Reflection.MetadataLoadContext" Version="$(RuntimeFrameworkVersion)" />
     <PackageVersion Include="System.ServiceProcess.ServiceController" Version="$(RuntimeFrameworkVersion)" />
     <PackageVersion Include="Validar.Fody" Version="1.9.0" />