Fix docker file issue

Author: StuartFerguson

MessagingService/Dockerfile

@@ -3,7 +3,7 @@
 FROM mcr.microsoft.com/dotnet/aspnet:5.0 AS base
 WORKDIR /app
 
-FROM mcr.microsoft.com/dotnet/sdk:5.0 AS build
+FROM mcr.microsoft.com/dotnet/sdk:5.0.102-ca-patch-buster-slim AS build
 WORKDIR /src
 COPY ["MessagingService/NuGet.Config", "."]
 COPY ["MessagingService/MessagingService.csproj", "MessagingService/"]