chore(deps): update dependency reactivemarbles.roslynhelpers to v1.2.8

Author: renovate[bot]

src/Splat.DependencyInjection.SourceGenerator/Splat.DependencyInjection.SourceGenerator.csproj

@@ -16,7 +16,7 @@
     <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" PrivateAssets="all" GeneratePathProperty="true" />
     <PackageReference Include="Microsoft.CodeAnalysis.Common" Version="4.0.1" PrivateAssets="all" GeneratePathProperty="true" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.0.1" PrivateAssets="all" GeneratePathProperty="true" />
-    <PackageReference Include="ReactiveMarbles.RoslynHelpers" Version="1.2.1" GeneratePathProperty="true" PrivateAssets="all" />
+    <PackageReference Include="ReactiveMarbles.RoslynHelpers" Version="1.2.8" GeneratePathProperty="true" PrivateAssets="all" />
     <PackageReference Include="ILRepack" Version="2.0.28" GeneratePathProperty="true" PrivateAssets="all" />
   </ItemGroup>