Use 9.0 SDK in Dockerfiles

Author: bording

src/ServiceControl.Audit/Dockerfile

@@ -1,5 +1,5 @@
 # Build image
-FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:9.0 AS build
 ARG TARGETARCH
 WORKDIR /
 ENV CI=true

src/ServiceControl.Monitoring/Dockerfile

@@ -1,5 +1,5 @@
 # Build image
-FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:9.0 AS build
 ARG TARGETARCH
 WORKDIR /
 ENV CI=true

src/ServiceControl/Dockerfile

@@ -1,5 +1,5 @@
 # Build image
-FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:9.0 AS build
 ARG TARGETARCH
 WORKDIR /
 ENV CI=true