chore: move cns from servercore to nanoserver

Signed-off-by: Evan Baker <rbtr@users.noreply.github.com>

cns/windows.Dockerfile

@@ -7,7 +7,7 @@ WORKDIR /usr/local/src
 COPY . .
 RUN GOOS=windows CGO_ENABLED=0 go build -a -o /usr/local/bin/azure-cns.exe -ldflags "-X main.version="$VERSION" -X "$CNS_AI_PATH"="$CNS_AI_ID"" -gcflags="-dwarflocationlists=true" cns/service/*.go
 
-FROM mcr.microsoft.com/windows/servercore:${OS_VERSION}
+FROM mcr.microsoft.com/windows/nanoserver:${OS_VERSION}
 COPY --from=builder /usr/local/src/cns/kubeconfigtemplate.yaml kubeconfigtemplate.yaml
 COPY --from=builder /usr/local/src/npm/examples/windows/setkubeconfigpath.ps1 setkubeconfigpath.ps1
 COPY --from=builder /usr/local/bin/azure-cns.exe azure-cns.exe