[ksqlDB.RestApi.Client]: upgraded images in Blazor sample's Dockerfile to .NET 9

Author: tomasfabian

Samples/Blazor.Sample/Dockerfile

@@ -1,11 +1,11 @@
 #See https://aka.ms/containerfastmode to understand how Visual Studio uses this Dockerfile to build your images for faster debugging.
 
-FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS base
+FROM mcr.microsoft.com/dotnet/aspnet:9.0 AS base
 WORKDIR /app
 EXPOSE 80
 EXPOSE 443
 
-FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
 WORKDIR /src
 COPY ["nuget.config", "."]
 COPY ["Samples/Blazor.Sample/Blazor.Sample.csproj", "Samples/Blazor.Sample/"]