Bump dotnet/aspnet from 7.0-alpine to 9.0-alpine

Bumps dotnet/aspnet from 7.0-alpine to 9.0-alpine.

---
updated-dependencies:
- dependency-name: dotnet/aspnet
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Dockerfile

@@ -15,7 +15,7 @@ WORKDIR /source/GetIntoTeachingApi
 RUN dotnet publish -c release -o /app
 
 # final stage/image
-FROM mcr.microsoft.com/dotnet/aspnet:7.0-alpine
+FROM mcr.microsoft.com/dotnet/aspnet:9.0-alpine
 
 WORKDIR /app
 COPY --from=build /app ./