Add csharp to backend image for tests

.github/DockerfileBackendTests

@@ -52,4 +52,6 @@ RUN unzip deno.zip && rm deno.zip && mv deno /usr/bin/deno
 RUN apt-get update \
     && apt-get install -y postgresql-client --allow-unauthenticated
 
-RUN rustup component add rustfmt
+RUN rustup component add rustfmt
+COPY --from=bitnami/dotnet-sdk:9.0.101-debian-12-r0 /opt/bitnami/dotnet-sdk /opt/dotnet-sdk
+RUN ln -s /opt/dotnet-sdk/bin/dotnet /usr/bin/dotnet

Dockerfile

@@ -199,4 +199,3 @@ RUN windmill cache ${APP}/hubPaths.json && rm ${APP}/hubPaths.json && chmod -R 7
 EXPOSE 8000
 
 CMD ["windmill"]
-