chore(deps): update dependency system.collections.immutable to 9.0.6 (#788)

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

Author: renovate[bot]

src/ReactiveUI.Validation/ReactiveUI.Validation.csproj

@@ -12,6 +12,6 @@
   </ItemGroup>
 
   <ItemGroup Condition="$(TargetFramework.StartsWith('netstandard')) or $(TargetFramework.StartsWith('net4'))">
-    <PackageReference Include="System.Collections.Immutable" Version="9.0.5" />
+    <PackageReference Include="System.Collections.Immutable" Version="9.0.6" />
   </ItemGroup>
 </Project>