[ksqlDb.RestApi.Client]: WorkerService example upgraded to .NET 9

Author: tomasfabian

Samples/ksqldB.RestApi.Client.WorkerService/ksqlDB.RestApi.Client.WorkerService/Dockerfile

@@ -1,9 +1,9 @@
 #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/runtime:8.0 AS base
+FROM mcr.microsoft.com/dotnet/runtime:9.0 AS base
 WORKDIR /app
 
-FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
+FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
 WORKDIR /src
 COPY ["ksqldB.RestApi.Client.WorkerService/ksqldB.RestApi.Client.WorkerService.csproj", "ksqldB.RestApi.Client.WorkerService/"]
 RUN dotnet restore "ksqldB.RestApi.Client.WorkerService/ksqldB.RestApi.Client.WorkerService.csproj"

Samples/ksqldB.RestApi.Client.WorkerService/ksqlDB.RestApi.Client.WorkerService/ksqlDB.RestApi.Client.WorkerService.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Worker">
 
     <PropertyGroup>
-        <TargetFramework>net8.0</TargetFramework>
+        <TargetFramework>net9.0</TargetFramework>
         <Nullable>enable</Nullable>
         <ImplicitUsings>enable</ImplicitUsings>
         <UserSecretsId>dotnet-ksqldB.RestApi.Client.WorkerService-C9138ED6-2AB5-44F3-A873-9FCD6EAA7B8E</UserSecretsId>