chore(deps): update dependency system.reactive to v7 (#1798)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Directory.Packages.props

@@ -51,7 +51,7 @@
     <PackageVersion Include="XunitXml.TestLogger" Version="8.0.0" />
     <PackageVersion Include="coverlet.collector" Version="10.0.1" />
     <PackageVersion Include="coverlet.msbuild" Version="10.0.1" />
-    <PackageVersion Include="System.Reactive" Version="6.1.0" />
+    <PackageVersion Include="System.Reactive" Version="7.0.0" />
     <PackageVersion Include="System.Collections.Immutable" Version="10.0.9" />
     <PackageVersion Include="System.Threading.Channels" Version="10.0.9" />
     <PackageVersion Include="Microsoft.Reactive.Testing" Version="6.1.0" />