build(deps): Bump ReactiveUI.Testing from 18.0.10 to 18.1.8 (#92)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

src/ReactiveMarbles.CacheDatabase.Tests/ReactiveMarbles.CacheDatabase.Tests.csproj

@@ -19,7 +19,7 @@
     </PackageReference>
     <PackageReference Include="FluentAssertions" Version="6.7.0" />
     <PackageReference Include="Microsoft.Reactive.Testing" Version="5.0.0" />
-    <PackageReference Include="ReactiveUI.Testing" Version="18.0.10" />
+    <PackageReference Include="ReactiveUI.Testing" Version="18.1.8" />
   </ItemGroup>
 
   <ItemGroup>