Update target framework and package references to .NET 9

Updated target framework in Api.csproj and MyWeatherHub.csproj from net8.0 to net9.0. Updated package references in Api.csproj: Microsoft.AspNetCore.OpenApi to 9.0.0, Swashbuckle.AspNetCore to 7.0.0. Updated package references in MyWeatherHub.csproj: Microsoft.AspNetCore.Components.QuickGrid to 9.0.0, Microsoft.Extensions.ApiDescription.Client to 9.0.0.

start-with-api/Api/Api.csproj

@@ -1,14 +1,11 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
-
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
-
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.8" />
-    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.7.3" />
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="9.0.0" />
+    <PackageReference Include="Swashbuckle.AspNetCore" Version="7.0.0" />
   </ItemGroup>
-
-</Project>
+</Project>

start-with-api/MyWeatherHub/MyWeatherHub.csproj

@@ -1,17 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
-
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
-
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.Components.QuickGrid" Version="8.0.8" />
-    <PackageReference Include="Microsoft.Extensions.ApiDescription.Client" Version="8.0.8">
+    <PackageReference Include="Microsoft.AspNetCore.Components.QuickGrid" Version="9.0.0" />
+    <PackageReference Include="Microsoft.Extensions.ApiDescription.Client" Version="9.0.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
   </ItemGroup>
-
-</Project>
+</Project>