Fix C# CI (#1734)

Author: RReverser

.github/workflows/ci.yml

@@ -116,6 +116,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: clockworklabs/spacetimedb-csharp-sdk
+          ref: staging
           path: spacetimedb-csharp-sdk
 
       - name: C# SDK tests

crates/cli/src/subcommands/project/csharp/StdbModule._csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="SpacetimeDB.Runtime" Version="0.11.*" />
+    <PackageReference Include="SpacetimeDB.Runtime" Version="0.12.*" />
   </ItemGroup>
 
 </Project>